Vascular Access In Children: Solve the Puzzle

 

Dr. Rawan Alrashed (@rawalrashed)

PEM Physician

PoCUS Fellow

Reviewed and edited by: Dr. David Lewis

 

Background

Pediatric vascular access is one of the challenging skills in the medical field especially during an emergency, different guidelines have been established to facilitate the choice of the proper IV access one of which is the miniMAGIC that was published in 2020.1 Choosing the right access is crucial for success taking in consideration the urgency of access, patient safety, infused fluid characteristic  to determine the right one especially with a peripheral IV catheter failure rate of 77% in the first attempt.2 Difficult intravenous Access score (DIVA) is one of the tool that can be used to evaluate the feasibility of a peripheral IV and accordingly, the best next step for IV line insertion where Subjects with a DIVA score of 4 or more were more than 50% likely to have failed intravenous placement on first attempt.3

 

Figure-1: DIVA score.4

Types of vascular access

  • Peripheral IV catheters (PIVCS)
  • Intraosseous Access
  • Central Venous Catheters (CVCs) (Non-tunneled) 
  • US guided Access
  • Umbilical Catheter
  • Surgical cutdown

 

Figure 2: Vascular Access Locations.5

Consideration in pediatrics4

  • Pain management is a critical step for the success of IV cannulation

Multiple choices are available starting from non-pharmacological distraction technique and non-nutritive sucking to the utilization of local anesthetic such as EMLA and LMX as well the needle-free lidocaine jet-injection

  • Enhancing visualization of vein by using tourniquet, transilluminator with any available light source.
  • Ultrasound guided peripheral IV access is the recommended current practice in difficult access.
  • Ultrasound guided central IV access is the standard of care currently in comparison to anatomical landmark in critical care setting.

Indication of IV access

Patient resuscitation.

Delivering fluids, medication, Blood sampling.

Hemodynamics monitoring as well arterial blood gas.

Contraindications

Infection at the insertion site.

Thrombosis of the vein.

Bleeding diathesis in central line is a relative contraindication.

In IO Access, fracture on the same bone as well pathological disorder predisposing to fractures is a contraindication.

Peripheral IV catheter (PIVC)

Different veins can be used for PIVC starting with dorsal veins of the hand, then the feet and then proceeding to other choices including scalp vein in infants, external jugular vein, antecubital and the great saphenous vein as in Figure-2.5

Technique:5

  1. Prepare instruments: cleansing solution, tourniquet, catheter needle, connecting tube, flush, dressing, gauze, and stabilizer tape.
  2. Size of catheter as in the table: utilize the smallest gauge and shortest catheter as possible with exception in resuscitation where larger bore gauge is preferable or in case of midline cannulation where longer catheter is preferable.
  3. Apply tourniquet proximal to the site of insertion to enhance visualization
  4. Identify proper vein by visualization, palpation and utilizing the transilluminator or infrared light
  5. Clean the skin as per the facility protocol
  6. Hold the needle between the thumb and forefinger with the dominant hand and stretch the skin with the other hand
  7. Enter with an angle of 10-30 degree then if blood seen shallow your angle to advance 1-2 mm then advance the catheter and once in pull your needle or retract it.
  8. Flush to confirm patency and no swelling at the site then stabilize your catheter

 

Neonate  Infant   Children Length
PIV 24-26G 22G 20G 2-6cm
Midline Access 22G 22G 20G 15-30cm

 

Table-1: Size of PIV catheter.

 

US guided peripheral vascular access

A recent RCT by Vinograd et.al. evaluated 167 children showed 85% success rate of first attempt with US guidance compared to 45% with traditional methods. Also US guidance resulted in shorter cannulation time, less redirection and fewer attempts.6 

Important consideration in US- guided PIV

  • The diameter and depth of the vein have been found determinate factors for success of cannulation in adult studies where very superficial (< 0.3 cm) and very deep (> 1.5 cm) veins are difficult to cannulate.7
  • The suggested veins are the cephalic vein in the forearm or the saphenous vein at the medial malleolus, while the antecubital vein might be an easy approach but the risk of brachial artery cannulation and the elbow bending make it less favorable. 7

Technique 7

  • Use a linear probe with 5-15 MHz ( Alternatively a hockey stick or MicroConvex might be useful)
  • Identify the vein and assess patency by being compressible and non pulsatile, for further confirmation utilize color or pulse wave doppler with augmentation to identify low status flow.

Longer catheter are preferable when using ultrasound guided insertion especially with a vein deeper then 0.5 cm to minimize the risk of dislodgment and infiltration (suggested to be longer than 2 cm). In a pilot study by Paladini, long catheter > 6 cm were associated with lower risk of failure in pediatric patients more than 10 years comparable to the short one <6 cm.8

  • Static or dynamic guidance are acceptable with preference of the latter. 
  • Two approach technique available with best outcome observed with out-of-plane in PIVC.

 

Out-of-plane (Short-Axis):
  • Consider using the middle point on the ultrasound machine to enhance alignment
  • The US wave perpendicular at right angle to the vessel.
  • The needle is inserted close to the probe at 20-30o angle then advance with meet and greet technique or dynamic needle tip positioning technique as in video

 

 

Pitfalls:

  • The needle shaft might be misidentified as the needle tip thus the importance of advancing the probe then the needle to maintain visualization of the tip only.  Also sweeping in the same plane can help to follow the needle proximal and distal to confirm the tip from the shaft.
  • Risk of posterior wall penetration and failure of cannulation.

 

In-Plane (Long-Axis):
  • The US beam is parallel to the vessel.
  • The whole needle shaft is visualized during insertion and advancement to the vein.
  • To facilitate visualization of needle “Ski left” technique can be used.

 

 

Pitfalls:

  • Maintaining the transducer static without any movement is difficult in small children as any movement would lead to loss of needle visualization, thus insertion will not be accurate (side lobe artifact)

No evidence of preferable technique in pediatrics but in adults out-of-plane proven to be superior for PIVC insertion.

 

How to Use US for PIVC:

https://www.coreultrasound.com/ultrasound-guided-peripheral-iv-access/

 

Intraosseous Access

It’s considered the best alternative IV access in emergencies (peri-arrest and arrest condition) after 2 failed attempts of PIVC within 60-90 seconds, AHA recommends IO catheter as first line access in cardiac arrest. Still the outcome of out of hospital cardiac arrest and best access need more delineation.4,5

Technique4

  • IO access can be accomplished using a manual needle or battery powered device such as EZ-IO or even a regular large bore needle.
  • Place the knee in slight flexion with padding.
  • Clean the skin and consider analgesia according to the urgency of the situation.
  • Insert the needle at 900 over the skin.
  • Remove the stylet and aspirate then infuse saline.
  • Confirmation of proper insertion by the needle standing still even if no backflow seen with lack of extravasation during fluid infusion.

Figure-2 (on green)  shows the possible site for IO insertion where the commonest one is the proximal tibial shaft about 1-2 cm from the tibial tuberosity avoiding the growth plate.

Complication4

  • IO needle is a temporary access that can not last for more than 24 hours
  • Longer use can predispose the child to complication including infection, thrombosis, fat embolism
  • Other complications of insertion include through-and-through penetration of the bone, physeal plate injury, pressure necrosis of the skin, compartment syndrome, osteomyelitis, subcutaneous abscess

 

Confirmation of IO by POCUS2

  • Use linear probe distal to the insertion site
  • Apply color doppler and observe for saline flush site
  • If above the bony cortical site or lateral or deep may indicate misplacement

 

Figure-3: POCUS confirmation of IO site.

 

 

Central IV Catheter (CIVC)

This an alternative longer duration route that can be utilized as an emergency line but less favorable compared to the IO during initial resuscitation. It is still considered a good choice in ill patients with difficulty of PIVC and failure of US guided peripheral access as well IO when fluid, high concentrated electrolytes and vasopressors are needed.4

The common site for insertion of non-tunneled CVC in pediatric is the internal jugular in critical care setting with higher success rate compared to femoral vein9 , but the femoral vein might be the first choice in PEM as it’s easily accessible and don’t interfere with resuscitation measures.10

Technique10

Always prepare your equipment and check them, also get consent when possible before attempting a central line

 

Age(years) weight (kg) Catheter gauge French gauge length (cm)
<1y 4-8 24 3 5-12
<1y 5-10 22 3-3.5 5-12
1-3y 10-15 20 4 5-15
3-8y 15-30 18-20 4-5 5-25
>8y 30-70 16-20 5-8 5-30

Table-2: CVC sizes.4

Anatomical Landmark5

Internal Jugular vein:

  • Under aseptic technique with proper draping, put the patient in Trendelenburg position and turn the head slightly to the other side.
  • Use the medial head of the sternocleidomastoid muscle or between the tow head at the level of the thyroid cartilage just lateral to the carotid artery guide your needle on a 45o  toward the ipsilateral nipple while aspirating during insertion until you feel loss of resistance and have a backflow.
  • follow with the guidewire into your needle and then dilator
  • Complete by  inserting the catheter line and fixing it.

Subclavian vein:

Directly below the clavicle at the junction of the lateral one third with the medial two third directing the needle toward the sternal notch

Femoral vein:

1-2 cm below the inguinal ligament medial to the femoral artery, guide the needle toward the umbilicus

 

US Guided CVC

The use of ultrasound guided insertion is considered the standard of care for central line insertion. Ultrasound use reduces the number of attempts and procedure duration, increases the successful insertion rate, and reduces complications compared to the skin surface anatomic landmarks technique.9

This can facilitate visualization, increase the success rate with 95% first attempt success rate of ultrasound-guided venous punctures compared to 34% of the anatomical landmark and decrease the rate of complication that would occur with the anatomical landmark.11

 

  • Always start by identifying the land mark on US before starting the procedure (vein is compressible and less pulsatile than the adjacent artery)
  • Probe position according to the site of insertion.  
  • Prepare the patient under aseptic technique as well the probe with sterile sheet and the ultrasound counsel unless you have assistance.
  • Infiltrate local anesthesia to the skin puncture site.
  • Utilize sterile gel on the outside of the sterile sheet or alternatively sterile water or saline
  • Use an out of plane technique to guide the needle into the vein (higher success rate).
  • Start by inserting the needle at 45 degree angle from the probe and the same distance away as the vein from the skin
  • Follow the dynamic needle tip positioning technique (meet &greet) to keep visualizing the needle tip while guiding it toward the vein
  • If confusing the needle tip with the shaft try to slide the probe proximal and distal until confirmation
  • Use the same steps in aspirating while inserting until having a backflow and confirming the needle is inside the vein lumen
  • Complete the steps as before and confirm the position of the guidewire by ultrasound.
  • Insert the central catheter and fix it with sutures and transparent dressing.

 

Internal jugular vein:

Subclavian vein

Femoral vein

 

Complication12

Confirm proper placement by US as well X-Ray

R/O complication as pneumothorax, hemothorax or hematoma, mis-displacement

Artery puncture, air embolism, thoracic duct injury, arrhythmia are possible complications.

 

Umbilical Catheter

  • Can be used in neonate up to 7 days old.
  • Apply tourniquet to umbilical stump then cut the upper dried part.
  • Identify the vein which is single and thin walled while arteries are two and thick wall.
  • Stent the vessel with a forceps then insert the catheter up to 3-4 cm until blood return (Do NOT advance further as the risk of complication and adverse events are high)

 

Venous Cutdown

It is uncommon access in pediatric patients with the availability of IO needle, if needed the classic site is the saphenous vein which is 2 cm superior and anterior to the medial malleolus.

 

 

Resources:

  1. Ullman AJ, Bernstein SJ, Brown E, et al. The Michigan Appropriateness Guide for Intravenous Catheters in Pediatrics: miniMAGIC. Pediatrics. 2020;145(Suppl 3):S269-S284. doi:10.1542/peds.2019-3474I.
  2. Delacruz N, Malia L, Dessie A. Point-of-Care Ultrasound for the Evaluation and Management of Febrile Infants. Pediatr Emerg Care. 2021;37(12):e886-e892. doi:10.1097/PEC.0000000000002300.
  3. Yen K, Riegert A, Gorelick MH. Derivation of the DIVA score: a clinical prediction rule for the identification of children with difficult intravenous access. Pediatr Emerg Care. 2008;24(3):143-147. doi:10.1097/PEC.0b013e3181666f32.
  4. Whitney R, Langhan M. Vascular Access in Pediatric Patients in the Emergency Department: Types of Access, Indications, and Complications. Pediatr Emerg Med Pract. 2017;14(6):1-20.
  5. Naik VM, Mantha SSP, Rayani BK. Vascular access in children. Indian J Anaesth. 2019;63(9):737-745. doi:10.4103/ija.IJA_489_19.
  6. Vinograd AM, Chen AE, Woodford AL, et al. Ultrasonographic guidance to improve first-attempt success in children with predicted difficult intravenous access in the emergency department: a randomized controlled trial. Ann Emerg Med. 2019;74:19–27.
  7. Nakayama Y, Takeshita J, Nakajima Y, Shime N. Ultrasound-guided peripheral vascular catheterization in pediatric patients: a narrative review. Crit Care. 2020;24(1):592. Published 2020 Sep 30. doi:10.1186/s13054-020-03305-7.
  8. Paladini A, Chiaretti A, Sellasie KW, Pittiruti M, Vento G. Ultrasound-guided placement of long peripheral cannulas in children over the age of 10 years admitted to the emergency department: a pilot study. BMJ Paediatr Open. 2018;2(1):e000244. Published 2018 Mar 28. doi:10.1136/bmjpo-2017-000244.
  9. Pellegrini S, Rodríguez R, Lenz M, et al. Experience with ultrasound use in central venous catheterization (jugular-femoral) in pediatric patients in an intensive care unit. Arch Argent Pediatr. 2022;120(3):167-173. doi:10.5546/aap.2022.eng.167.
  10. Skippen P, Kissoon N. Ultrasound guidance for central vascular access in the pediatric emergency department. Pediatr Emerg Care. 2007;23(3):203-207. doi:10.1097/PEC.0b013e3180467780.
  11. De Souza TH, Brandão MB, Santos TM, Pereira RM, Nogueira RJ. Ultrasound guidance for internal jugular vein cannulation in PICU: a randomised controlled trial. Arch Dis Child. 2018; 103(10):952-6.
  12. Georgeades C, Rothstein AE, Plunk MR, Arendonk KV. Iatrogenic vascular trauma and complications of vascular access in children. Semin Pediatr Surg. 2021;30(6):151122. doi:10.1016/j.sempedsurg.2021.151122

 

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Volume Status Assessment in ED: Beyond the Vitals

Dr. Rawan Alrashed (@rawalrashed)

PEM Physician

PoCUS Fellow

Reviewed and edited by: Dr. David Lewis

Case

A 55 year old man known to have hypertension, diabetes, atrial fibrillation, chronic kidney disease presenting with 1 week H/O fever, SOB, chest pain, cough, fatigability, looking distressed on exam with HR 110, SpO2 of 86% on RA and BP of 87/45. No audible crackles or gallop rhythm, bilateral pitting edema noticed.

So, you are asking yourself should your next step be Fluids or Diuresis ??

Background

Patient presenting to the emergency department as critically ill with shock status presents a challenge in the initial hour to balance their fluid requirements with their volume status to reach an improvement in hemodynamics without causing harm.

Volume status assessment and fluid responsiveness have been investigated using multiple measures ranging from physical examination to laboratory work up to invasive measures. Despite all that, no single or multiple factor have been sensitive or specific enough to guide further fluid management. Currently, PoCUS is progressing widely in aiding the emergency physician to take a decision in assessing patient’s  fluid vs vasopressor vs diuretic needs and guide further resuscitation. PoCUS is noninvasive, readily available, reproducible test that can be augmented with other measures to guide fluid management (1).

 

Pathophysiology

To simplify fluid responsiveness, patients are assessed on accordance of the Frank-Starling curve. Patients will respond to fluid administration if they are on the ascending portion of the Starling curve and no benefit will be added if they are at a plateau where more harm can occur which is difficult to be predict form physical examination solely (2).

 

Figure 1: Frank Starling Law

 

Fluid Challenge

Traditionally volume responsiveness has been assessed by small fluid bolus challenge. A safer alternative to this is passive leg raise (PLR) which is an autotransfusion where you mobilize about 300-500 ml of intravascular volume from the lower limb to the heart by raising the patient legs from 0o to 45o. A Pre-Post assessment of stroke volume within 30-90 sec from PLR can be done to measure the difference where change of 10% consider to be responsive.

This have been shown to have a sensitivity of 77% to 100%, and a specificity of 88% and 99% (1).

 

Figure 2: Passive Leg raising technique (uptodate)

 

Volume Status Assessment

PoCUS have been used in volume status assessment and fluid responsiveness using multiple surrogates which can be classified as follows for simplification:

  1. Cardiac PoCUS: core and advanced.
  2. Stroke volume Assessment: VTI of LVOT/Carotid artery.
  3. Vascular Assessment: IVC, IJV.
  4. Venous Congestion: Hepatic, portal, & intra-renal doppler.
  5. Lung PoCUS.

 

1) Cardiac PoCUS

The target of Cardiac PoCUS is to assess for possible causes of hypotension and shock status using the RUSH or SHoC protocol (3).

 

Figure 3: SHoC Protocol (3).

 

2) Cardiac Output Assessment

Two measures can be used to assess fluid responsiveness: the left ventricular outlet tract (LVOT) and the carotid artery where you assess the velocity time integral (VTI) representing the column of blood passing through the vessel through time. This can be used as surrogate of fluid responsiveness before and after the PLR where a change of 10-15% consider as fluid responsive (4).

 

a. LVOT measurements

Cardiac output variation of greater than 14% has a high positive predictive value for the patient being fluid responsive while values less than 10% are associated with a high negative predictive value (1)

Cardiac output (mL/min) = Stroke Volume (mL/cycle) x Heart Rate (bpm)

Stroke Volume= LVOT area    x    LVOT VTI

 

PoCUS Technique (4)

  • Using the cardiac phased array probe to get apical 5 chamber view and parasternal long axis view.
  • Apical five chamber view, with visualization of the LVOT (A).
  • Pulsed wave Doppler interrogation of the LVOT. The interrogation window is placed just above the aortic valve, and the line of interrogation is positioned parallel to the long-axis of the LVOT itself (B).
  • Measuring the area under the curve of the LVOT Doppler waveform to derive the velocity time integral (C) .
  • Diameter of the LVOT, measured from a parasternal long-axis view (D)

Figure 4: Stroke volume measurement at the LVOT.

 

 

b. Common Carotid Artery

Two measurement are applied to the carotid artery: the carotid blood flow and the corrected carotid flow time index. These measure are recently established in the field of cardiac output assessment and accuracy is still under debate with further studies needed.

 

  • The carotid blood flow is the integral of blood volume that is ejected through the carotid artery with each cardiac cycle. An increase of carotid blood flow by 20% after PLR is indicative of fluid responsiveness with a sensitivity of 94% and specificity of 86% (6).

 

  • The corrected carotid flow time index  (CFTI) representing the flow time between the onset of systole and the closure of the aortic valve as the duration of the full cardiac cycle. A change in the CFTI of 25% following PLR was found to have high specificity but a low sensitivity accordingly a cutoff values of 10% to 15% are more typical, still further studies are needed to specify the accurate cut off value (4).

 

PoCUS Technique (4,5)

a. The linear transducer is placed at approximately at the level of the thyroid cartilage, with the orientation marker pointed toward the patient’s head (A).

b. The Carotid artery identified in long-axis and the bulb before the bifurcation visualized and the doppler is applied within 2–3 cm proximal to the carotid bulb, interrogation line (green) has also been angled to make it more parallel to the long-axis of the artery.

c. The Doppler angle correction cursor is placed parallel to the direction of blood flow with insonation angles <60° .

d. Carotid artery Doppler waveform with measurement of the systolic flow time (SFT) and total cycle time (CCT).

e. Calculate the corrected flow time index using the following formula (Figure-5):

                                           CFTI=SFT/√CCT

f. Calculate the carotid blood flow using velocity time integral tracing and carotid diameter (Intima to intima)  then apply it in this formula (Figure-6):

                                     blood flow=π×(carotid diameter)2/4×VTI×heart rate

 

Figure-5: Corrected Carotid Flow Time Index Measurement (4).

 

Figure-6: Carotid Blood Flow measurement (5).

 

 

 

3) Vascular Assessment

a. Inferior vena cava (IVC)

Measurements of IVC diameter and respiratory variation with the collapsibility index as a predictor of fluid responsiveness was found to be having pooled sensitivity and specificity of 63% and 73% respectively (7).  

PoCUS Technique (8)

  • Use the curvilinear or phased array probe.
  • placed in the sub-xiphoid space with the transducer flat against the abdomen identifying RA and gradually fanning the probe until the intrahepatic IVC can be identified.
  • The probe is then rotated 90 degrees with the marker toward patient head to obtain the IVC in long axis view.
  • IVC diameter is measured 2 cm inferior to the cavo-atrial junction or about 1 cm inferior to the branching of the hepatic veins (Figure 7).
  • M-mode can be used to track IVC collapse during inspiration in spontaneously breathing patients.

Figure-7: IVC and measurement of respiratory variation (Collapsibility Index)

 

Measurements:

Collapsibility Index (Caval Index)

The collapsibility index=(maximal vessel diameter – minimal vessel diameter)÷maximal vessel diameter

It has been demonstrated that venous collapsibility may be inversely proportional to CVP: a 1 mmHg change in central venous pressure correlates to about 3.3% change in IVC collapsibility (9).

 

IVC diameter (cm) CI (%) CVP (mmHg)
<1.5 100% <0-5 Volume depleted
1.5-2.5 >50% <10 Less predictive of responsiveness
1.5-2.5 <50 >10
>2.5 0% >20 Volume overload

 

Important to note that sole interpretation of the IVC for volume assessment was found to be poorly correlating and thus should be used in conjunction with  other measures and integrated on patient presentation (9).

 

b. Internal Jugular Vein (IJV)

Internal jugular vein is used for the assessment of the central venous pressure in comparable way to IVC. A small study of non-ventilated patients who were simultaneously undergoing CVP monitoring, a mean IJV diameter of 7 mm correlated with a CVP of 10 mmHg (8). 

Collapsibility index of the IJV with change of 39% consider the patient as volume depleted but this carries a limitation of the intrabdominal/ intrathoracic pressure effects (4).

PoCUS Technique

  • Use the linear Probe
  • Identify the IJV in transverse plane then rotate the probe 90o toward the patient head.
  • Image of IJV is obtained where it narrows into a paintbrush appearance (Figure 8).
  • The height where the IJV tapers correlates with jugular venous distension.
  • The IJV diameter is measured using M-mode through several respiratory cycles, and the end expiratory diameter is used as the final measurement.

Figure-8: Internal Jugular vein

 

4)Venous Congestion (VEXUS):

This includes assessment of the Hepatic/Portal/Intrarenal veins wave forms which has been correlated to the level of venous congestion thus estimating the end organ volume effects.

Hepatic Vein Doppler mainly reflects the right atrium filling pattern, portal and intrarenal venous Doppler provide additional information about right atrial filling pressure and its correlation with congestive organ injury (10).

 

PoCUS Technique (9)

Hepatic Vein Doppler

  • The probe is placed over the liver in the subcostal position to visualize the middle hepatic vein. Pulsed-wave Doppler is used 2-4 cm from where the hepatic vein drains into the IVC.

Findings: The waveform of the hepatic vein is reversed with higher velocities seen in diastole in states of volume overload. In severe volume overload, retrograde flow is seen in systole (Figure 9)

 

Figure-9: Hepatic vein doppler different wave forms (11).

 

Portal Vein Doppler

  • Moving towards the portal vein, the transducer is placed in the right mid-axillary line

Findings: Flow through the portal vein is normally monophasic, but in the presence of hypervolemia, pulsatility will be present. This can be quantified using the pulsatility index where a pulsatility index greater than 50% indicates severe volume overload.

 

Figure 10: Portal vein doppler wave forms (11).

 

Intra-renal Doppler

  • The curvilinear transducer is placed on the posterior axillary line

Findings: A normal Doppler waveform is continuous. With increasing venous congestion, there is a decrease in the systolic component of the wave with progression to biphasic (systolic/diastolic phases), and with severe renal congestion, there is complete absence of systolic flow showing only diastolic phase.

 

Figure 11: Intra-renal doppler wave forms (11).

 

Figure-12: the change in the venous doppler according to progression of venous congestion (10).

 

Figure -13: VExUS grading system for venous congestion using IVC and different venous doppler wave form for categorization.

 

5)Lung Ultrasound 

A meta-analysis showed that LUS is 88% sensitive and 90% specific for acutely decompensated heart failure and was more sensitive at detecting pulmonary edema than CXR (8).

Another meta-analysis determined the sensitivity and specificity of ultrasound for detection of pleural effusions as 93% and 96% respectively. The sensitivity approaches 100% with pleural effusions >100 mL in volume (8).

PoCUS Technique

  • Use the linear or curvilinear probe.
  • In longitudinal plane, along the midclavicular, midaxillary line then the posterior-lateral point.

Findings:

  • B-lines are hyperechoic vertical lines extending from the pleura down to the bottom of the US image (Figure 14). Two or fewer B-lines in each section is considered normal
  • Pleural effusion can be identified with presence of V-sign (extension of vertebral line proximal to the diaphragm (Figure-15) .  

 

Figure 14: B-Lines

Figure 15: Pleural effusion

 

 

 

 

 

 

 

 

 

 

Case Conclusion

Patient was found to have reduced LV function with Dilated IVC and CI of 15%, VExUS grade 2. Assessment of COP after PLR didn’t show a proper change thus patient was started on diuretic and respiratory support with consideration of inotropic support. 

Conclusion

The table below (8) shows a summary of the evidence related to the different used marker for volume assessment from physical exam to the use of PoCUS. Thus, it is imperative that we do not rely on one single tool, but rather integrate both pertinent physical examination and POCUS findings for better probability of coming to the right decision.

 

 

References

  1. Pourmand A, Pyle M, Yamane D, Sumon K, Frasure SE. The utility of point-of-care ultrasound in the assessment of volume status in acute and critically ill patients. World J Emerg Med. 2019;10(4):232-238. doi:10.5847/wjem.j.1920-8642.2019.04.007.
  2. Praveen P., Shanmugam L., Prasath, P. A review of role of lung ultrasound and clinical congestion score in acute left ventricular failure. International Journal of Advances in Medicine. 2020;7. 720. 10.18203/2349-3933.ijam20201130.
  3. Atkinson P, Bowra J, Milne J, et al. International Federation for Emergency Medicine Consensus Statement: Sonography in hypotension and cardiac arrest (SHoC): An international consensus on the use of point of care ultrasound for undifferentiated hypotension and during cardiac arrest – CORRIGENDUM. CJEM. 2017;19(4):327. doi:10.1017/cem.2017.31.
  4. Millington SJ, Wiskar K, Hobbs H, Koenig S. Risks and Benefits of Fluid Administration as Assessed by Ultrasound. Chest. 2021;160(6):2196-2208. doi:10.1016/j.chest.2021.06.041.
  5. Ma IWY, Caplin JD, Azad A, et al. Correlation of carotid blood flow and corrected carotid flow time with invasive cardiac output measurements. Crit Ultrasound J. 2017;9(1):10. doi:10.1186/s13089-017-0065-0.
  6. Marik PE LA, Young A, Andrews L. The use of bioreactance and carotid Doppler to determine volume responsiveness and blood flow redistribution following passive leg raising in hemodynamically unstable patients. Chest. 2013;143(2):364-370. doi:10.1378/chest.12-1274.
  7. Long E, Oakley E, Duke T, Babl FE. Does Respiratory Variation in Inferior Vena Cava Diameter Predict Fluid Responsiveness: A Systematic Review and Meta-Analysis. Shock (Augusta, Ga). 2017;47(5):550-559.
  8. Kearney, D., Reisinger, N., & Lohani, S. (2022). Integrative Volume Status Assessment. POCUS Journal7(Kidney), 65–77.
  9. Argaiz Eduardo R, Koratal A., Reisinger N. Comprehensive Assessment of Fluid Status by Point-of-Care Ultrasonography. Kidney360
  10. Galindo P, Gasca C, Argaiz ER, Koratala A. Point of care venous Doppler ultrasound: Exploring the missing piece of bedside hemodynamic assessment. World J Crit Care Med. 2021;10(6):310-322. Published 2021 Nov 9. doi:10.5492/wjccm.v10.i6.310.
  11. Dinh, V. (n.d.). Vexus ultrasound score – fluid overload and venous congestion assessment. POCUS 101. Retrieved March 29, 2022, from https://www.pocus101.com/vexus-ultrasound-score-fluid-overload-and-venous-congestion-assessment/. 

 

 

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Scrotal Pain – Scrotal PoCUS in a nutshell

Rawan Alrashed (@rawalrashed)

PEM Physician

PoCUS Fellow


Background

Acute Scrotal pain represent 0.5% of Emergency department visit, less than 25% of those are due to testicular torsion (1). Clinical history and physical examination don’t consist a definitive tool to diagnose the problem especially when presentation of different causes of scrotal pain can overlap. Testicular torsion doesn’t always present with the typical acute onset of pain as gradual onset was found in 25% of presentation which is described for the epididymo-orichitis (2-3). Scrotal pathology is divided into the 4 following groups: torsion, trauma, infection, and tumors, often described as the scrotum’s “4 T’s (4).

 

Review on how to approach Acute scrotal pain can be found on this post:

The Acute Scrotum


Anatomy

The testicles originate in the posterior abdominal wall in embryonic life then migrates to the scrotum, in case of failure of migration presentation of acute scrotum can be along the abdomen, inguinal canal.

 

       

 

Figure-1 Anatomy on Transverse and Longitudinal plane (Radiology Key)(5) 

 

The testicle is enveloped by a fibrous capsule called the tunica albuginea, which projects into the testis to form the mediastinum testis. The tunica vaginalis is a two-layered membrane that covers the tunica albuginea. Multiple testicular seminiferous tubules run toward the mediastinum and coalesce into a network of channels called the rete testis. These channels pass through the mediastinum and tunica albuginea to form the epididymal head, body, and tail ducts, which continue as the vas deferens. The spermatic cord contains the vas deferens, testicular vessels, pampiniform venous plexus, and nerve (6).


PoCUS Technique

  • Patient should be in supine position.
  • Use a towel under the scrotum for elevation and support and a second towel to cover and retract the penis of the scrotum.
  • Use a linear high-frequency (>7MHz) transducer with broad bandwidth.
  • Scan in transverse and sagittal planes.
  • Assess the size and texture of each testicle and look to the surroundings including the epididymis and tunica vaginalis for fluids.
  • Use comparison by visualizing both testicle in transverse plane.
  • Use Color and spectral Doppler imaging for the assessment of blood flow.
  • Images of the inguinal canal and spermatic cord can be obtained in the upright position during Valsalva maneuver to evaluate for inguinal hernias and varicoceles, respectively.

N.B. Doppler settings should be optimized to maximize detection of low-velocity flow. Color Doppler gain should be adjusted to eliminate artifacts. This can be done by adjusting the scale of flow on the normal testis then use it to visualize the abnormal one. (6)

 

Video on how to do the scan (7):

 


Normal Findings

Figure 2- Ultrasound Anatomy: a- Transverse view, b- sagittal view (6)

 

  • Scrotal wall is heterogeneous and the wall thickness ranges from 2 to 8mm.
  • The normal adult testicle is oval and measures approximately 5×3×2 cm, with a homogeneous echotexture and diffuse intermediate level echogenicity.
  • The tunica albuginea appears as a thin hyperechoic rim encasing the testicle, which invaginates in the central testicle as a hyperechoic band corresponding to the mediastinum testis.
  • The tunica vaginalis can be identified as a thin hyperechoic line, but this structure is not routinely visualized in the absence of hydrocele.
  • The epididymis is best visualized on longitudinal views and appears isoechoic to slightly hypoechoic relative to the adjacent testis.
  • The spermatic cord has a straight course from the external inguinal ring along the posterior border of the testicle, with a normal transverse diameter of less than 5mm. (6)

 

– Comparing testicular echogenicity bilaterally (Q-path)

– Comparing bilateral Testicular blood supply and notice the low flow scale (Q-path)


 

 

 

 

 

 

 

 


PATHOLOGY

1.VASCULAR 

 

Testicular Torsion (Torsion of the spermatic cord)

Testicular Torsion is a clinical diagnosis mainly affecting children with two age peaks at 1 year and adolescence (6). TWIST score can help in risk stratifying  the patients which was developed by urologist and validated in pediatric age group in emergency setting (8).

REMEMBER

Time is testicle, So once suspected involve surgical specialty for De-torsion. As the salvage rate is as high as 80%-100%  if it was repaired within 6 hours of symptom onset then drops to 20% after 12 hours (9).

If diagnosis couldn’t be made clinically, Scrotal ultrasound can help with the use of color and spectral doppler to rule in this diagnosis.

 

Findings:

It will depend on the timing of presentation

Early (within 6 hours):

  • Abnormal position.
  • Normal echogenicity could be seen early.
  • Twisting of the spermatic cord (most specific) (“whirlpool sign”)
  • Reduced venous flow.
  • Later testicular enlargement within the 6 hours due to tissue edema.
  • Scrotal wall thickening, and secondary hydrocele may also be observed. (6,9)

After 6 hours Reduced arterial blood supply with high resistance flow pattern compared to normal flow.

Late(After 24 h):

  • Testicular heterogeneity, hypo-echogenicity due to infarction and hemorrhage (at this stage salvageability is less likely (10).

 

Normal right testis (Q-path)

Abnormal echogenicity of left testis (Q-path)

Absence of color flow on this image (Q-path)

 

 

 

 

 

 

 

Whirlpool sign (11)

 

 

Important to keep in mind:

-In case of Partial torsion, the previous findings might not fully manifest and the scan could be falsely negative, still the abnormal spermatic cord can be seen as well on spectral doppler the arterial flow will be either absent or reversed diastolic flow.

-In Case of Torsion- De-torsion, rebound reperfusion with hyperemia may make the diagnosis difficult and confusing, so regular monitoring and re-scan could help in reaching the diagnosis (6,9).

 

Video explaining the findings on PoCUS and spectral doppler wave :

 

 


Torsion of testicular appendage

It’s the commonest presentation of pediatric testicular pain. This appendage is usually pedunculated and is present in more than 80% of children. It is located at the superior aspect of the testis in the groove between the testicle and the epidydimal head.

Findings:

  • Appendages are more readily apparent in the presence of a hydrocele.
  • Enlarged, rounded, extra-testicular masses, with mixed hyperechoic and heterogeneous echotexture depending on the degree of ischemia.
  • Absent flow on color Doppler, and hyperemia of the surrounding structures. (6)

 

normal appearing testicular appendix with hydrocele (11)

Hyperechoic torsion appendage (11)

Absent blood supply inside the appendage with hyperemia around it (11)

 

 

 

 

 

 

 


2. INFECTIOUS

 

Epididymitis and epididymo‑orchitis

Always try to scan the Epididymis from head to tail (some infection may be limited to the  tail) then compare the findings to the unaffected site.

Findings: 

  • Heterogenous echogenicity.
  • Enlargement in size.
  • Increase in color flow doppler.
  • Secondary findings includes Hydrocele and scrotal wall thickening.

The primary infection might get complicated and develop Abscess or Pyocele or end up with infarction and reversal arterial diastolic flow (6,9).

Enlarged epididymis (Q-path)

Increase flow on color doppler (Q-path)

 

 

 

 

 

 

 

 

 

Fournier gangrene

It’s a polymicrobial necrotizing fasciitis of the perineal, perianal, or genital areas. This diagnosis is clinical though the characteristic crepitus could only be found in 19-64% of cases. It’s critical that if this diagnosis is suspected, treatment should not be delayed for imaging confirmation. The modality of choice for diagnosis is CT scan (12).

Findings on US:

  • Diffuse subcutaneous tissue thickening.
  • Perifascial fluid accumulation.
  • Bright echogenic foci with dirty shadowing and reverberation artifacts corresponding to the underlying soft tissue gas. (12)

 

Thickening of scrotal wall with hydrocele and air reverberation artifact (13)

 


3. TRAUMA

The American Urological Association recommends surgical exploration in case of testicular trauma to delineate the extent of injury and should be within 72 hours as the rate of salvage up to 90% of blunt testicular rupture cases; But when surgery is delayed beyond this time point, the orchiectomy rate is 45%. (6,9)

 

Testicular Rupture: 

  • A tear in the tunica albuginea that results in extrusion of testicular contents.
  • Radiology US sensitivity 100% Specificity 93.5%.
  • Images will show heterogeneous testicle, contour abnormality, and disruption of the tunica albuginea.
  • Color Doppler imaging demonstrates focal or diffuse loss of vascularity.

Testes look heterogenous with irregular wall and abnormal blood supply (11)

Complete loss of the testicle contour (13)

 

 

 

 

 

 

 

 

 

 

 

 

Testicular fracture 

Disruption of the testicular parenchyma with preserved testicular shape and integrity of the hyperechoic tunica albuginea. The fracture plane appears as an avascular linear hypoechoic band extending across the parenchyma.

It’s critical to identify blood flow on color doppler to determine salvageability(9,10).

 

Scrotal hematoma

Depend on the chronicity of the evolving blood products; hematoceles and focal testicular, epididymal, and scrotal wall hematomas are acutely hyperechoic with decreasing echogenicity and increasing complexity (septa, loculations, and fluid levels) as they evolve to subacute and chronic phases. Hematomas have no internal flow on color and power Doppler images(9,10).

 


4. OTHERS

 

Testicular tumors:

  • Well-defined, hypoechoic or heterogeneous echogenicity intra-testicular lesion.
  • Might also see calcifications, micro-lithiasis, and necrosis.
  • Low level echoes with increased blood flow on color Doppler.(9)

 

multiple hypoechoic area with micro-lithiasis (11)

 

Varicocele:

  • Normal diameter of the pampiniform plexus veins range from 0.5 to 1.5 mm, the diameter of the main draining vein measuring up to 2 mm.
  • When this diameter increases, the collection of tortuous elongated veins seen posterior to testes.
  • Primary varicocele is almost always (98%) left sided due to venous drainage into the renal vein, contrary to direct drainage of the right vein into the inferior vena cava.
  • Secondary varicoceles are bilateral in up to 70%.

Dilated vein (worm like appearance) (14)

 

augmented vascularity with Valsalva (14)

 

 

 

 

 

 

 


 

 

The Evidence

  • Color and power Doppler ultrasonography reported sensitivity ranges between 86% and 98%, specificity up to 100%, and accuracy up to 97% by radiologist(9).
  • Friedman et.al. reported an agreement rate of  70% accuracy of all performed acute scrotum point-of-care ultrasound with final diagnosis(15).
  • Testicular torsion showed a sensitivity of 100% and Specificity of 99.1% with 73 minutes difference between the emergency physician and the radiologist acquiring the results(15).
  • For the other applications, still the evidence to be established but Blaivas et al. in a sample of 36 patients found the accuracy of emergency physician diagnosis compared to radiological studies was 95% sensitive and 94% specific(16).

 

Limitation and pitfalls

  • Normal variant
  • Overlapping of pathological findings might interfere with diagnosis, so clinical correlation is needed.
  • PoCUS in the emergency department is mainly a Rule In NOT out, So if no testicular torsion is identified it doesn’t mean that it’s ruled out.
  • Absence of scrotal pathology might signify an abdominal one especially if you identified undescended testes.

 

Bottom line:

  • Presentation of scrotal pathology could overlap greatly, and PoCUS can aid in delineating the diagnosis.
  • Most critical for emergency physician is to identify testicular torsion as time here is your enemy so PoCUS can assist in Ruling in this diagnosis with accuracy reaching 100%.

 


References

  1. Blaivas M, Sierzenski P, Lambert M. Emergency evaluation of patients presenting with acute scrotum using bedside ultrasonography. Acad Emerg Med. 2001;8(1):90-93.
  2. Cos LR, Rabinowitz R. Trauma-induced testicular torsion in children. J Trauma. 1982; 22:244–6.
  3. Melekos MD, Asbach HW, Markou SA. Etiology of acute scrotum in 100 boys with regard to age distribution. J Urol.1988; 139:1023–5.
  4. Wittenberg AF, Tobias T, Rzeszotarski M, et al. Sonography of the acute scrotum: The four T’s of testicular imaging. Curr Probl Diagn Radiol 2006;35:12-21.
  5. Testicular Ultrasound | Radiology Key.
  6. Sweet DE, Feldman MK, Remer EM. Imaging of the acute scrotum: keys to a rapid diagnosis of acute scrotal disorders. Abdom Radiol (NY). 2020;45(7):2063-2081.
  7. Badar Bin Bilal Shaf, 2018, Testicular Evaluation using Bedside Ultrasonography. (Testicular Evaluation using Bedside Ultrasonography: Practice Essentials, Indications, Positioning (medscape.com)
  8. Frohlich LC, Paydar-Darian N, Cilento BG Jr, Lee LK. Prospective Validation of Clinical Score for Males Presenting With an Acute Scrotum. Acad Emerg Med. 2017;24(12):1474-1482.
  9. Cokkinos DD, Antypa E, Tserotas P, et al. Emergency ultrasound of the scrotum: a review of the commonest pathologic conditions. Curr Probl Diagn Radiol. 2011;40(1):1-14.
  10. Rebik K, Wagner JM, Middleton W. Scrotal Ultrasound. Radiol Clin North Am. 2019;57(3):635-648.
  11. Radiopedia (Radiopaedia.org, the wiki-based collaborative Radiology resource).
  12. Levenson RB, Singh AK, Novelline RA (2008) Fournier gangrene: role of imaging. Radiographics 28:519-528.
  13. The Pocus Atlas (TPA (thepocusatlas.com)
  14. Liftl (Ultrasound Case 105 • LITFL • POCUS Top 100).
  15. Friedman N, Pancer Z, Savic R, et al. Accuracy of point-of-care ultrasound by pediatric emergency physicians for testicular torsion. J Pediatr Urol. 2019;15(6):608.e1-608.e6.
  16. Blaivas M, Sierzenski P, Lambert M. Emergency evaluation of patients presenting with acute scrotum using bedside ultrasonography. Acad Emerg Med. 2001;8(1):90-93.
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DVT PoCUS: When?, Where?, How? and What to do next?

 

Dr. Kyle Traboulsee

EM Physician, PoCUS Fellow

Reviewed by Dr. David Lewis

Copyedited by Dr. Rawan Alrashed 

 


Background

Lower extremity deep vein thrombosis (DVT) is a common, and potentially life-threatening vascular condition, with an annual incidence of 1 per 1000 adults. If left untreated, it may progress to pulmonary embolism, which is associated with a higher mortality. Therefore, accurate and timely diagnosis and treatment are incredibly important. (1,2,3)

An initial approach to the diagnosis of DVT involves risk stratification, often with the clinical risk score “Well’s score”, in conjunction with D-dimer assays. Based on the associated pre-test probability of the above risk stratification, further imaging may be required.

Although the gold standard for the diagnosis of DVT has traditionally been contrast venography, Duplex ultrasonography has become the standard of care due (in large part) to its lack of radiation and intravenous contrast, as well as widespread availability. This elective scan evaluates from groin to ankle and can take upwards of 1 hour depending on the difficulty of the individual exam. Studies have shown that a simplified ultrasound technique, limited to proximal segments of the femoral and popliteal veins using compression alone has a high sensitivity and specificity for proximal DVT detection. (2,4)

Point of care ultrasound (POCUS) has been increasingly used by emergency room physicians to assess for proximal lower extremity DVTs, with studies finding comparable diagnostic accuracy to radiology or vascular lab-performed duplex ultrasonography for detection of proximal DVT. (2)

 

Anatomy

 

Figure 1: Veins of the lower extremity (5)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The venous anatomy of the lower limb is relatively simple. The most proximal vein of interest is the Common Femoral Vein (CFV), which gives off the great saphenous vein (a superficial branch). Distal to this, the Common Femoral Vein should bifurcate into the Deep Femoral Vein, and Femoral Vein.

 

       N.B: the Femoral Vein also known as the Superficial Femoral Vein, but because it is still considered a deep vein with respect to the diagnosis of deep vein thrombosis, it is usually referred to as simply the Femoral Vein.

 

As the femoral Vein travels distally, it enters the adductor canal, passing posterior to the knee, and becomes the popliteal vein. The popliteal vein gives rise to three deep veins at the level of the calf: the perineal vein, anterior tibial vein, and posterior tibial vein. (5)

 

DVT POCUS protocols

There are multiple POCUS protocols with respect to lower extremity DVT evaluation, ranging from a 2-point ultrasound scan to a whole leg protocol. The more commonly studied, and utilized, protocols in the emergency department are referred to as the 2-point compression study and 3-point compression study. (1,2,5)

(It should be noted that the “points” are regions being scanned, opposed to distinct, singular points).

 

Figure 2: DVT protocols (5)

 

 

2-point compression study

This study evaluates the:

  • common femoral vein
  • popliteal vein

The common femoral vein is evaluated from the inguinal ligament until it becomes the femoral vein, including the junction of the common femoral vein and greater saphenous vein (CFV-GSV). Ensure this scan includes at least 1-2cm above and below the CFV-GSV junction. (2)

The popliteal vein is assessed from the popliteal fossa until it trifurcates. (2)

 

3-point compression study

This technique evaluates the:

  • Common femoral vein
  • Femoral vein
  • Popliteal vein.

Like the “2-point” examination, the common femoral vein is evaluated from the inguinal ligament until it becomes the femoral vein (including the CFV-GSV junction). The femoral vein is then further evaluated at least 2 cm distal to the bifurcation of the femoral vein and deep femoral vein. Some variations on the 3-point protocol may suggest continued evaluation of the femoral vein distally as it transitions to the popliteal vein. (2,4,5)

 

PoCUS Technique (3-point compression technique)

The linear array is the probe of choice for this scan.

 

 Femoral Veins

 

  1. Position the patient by raising the head of the stretcher 30 degrees and placing the patient in reverse Trendelenburg (if able). This allows distension of the lower limb veins. Slightly flex the knee and externally rotate the hip. (4,5)
  2. Place the probe along the inguinal ligament in the transverse plane midway between the pubic symphysis and anterior superior iliac spine and identify the common femoral vein (CFV). The common femoral artery and vein should be side by side, with the artery lateral to the vein.
  3. Ensure that you are at the most proximal part by sliding the probe proximally towards the abdomen until the CFV become in the far field obscured by bowel gases (most proximal point) then slide the probe distally and  Apply firm pressure with the probe until the vein collapses completely, or the artery begins to collapse without full collapse of the vein (which could indicate a DVT). (4,5)

 

Fig 3: Common femoral vein (5)

CFA: Common femoral artery
CFV: Common femoral Vein (5)

CFV compression (5)

 

 

 

 

 

 

 

 

 

 

 

 

 

4. After that slowly slide the probe distally, stopping every centimeter (or every width of the probe head), to compress the vein, ensuring it flattens completely. The end point of the scan is 1-2 cm distal to the bifurcation of the common femoral vein into the deep femoral vein and femoral vein. (4,5)

a. Within the first 1-2 cm, the great saphenous vein will branch off from the common femoral vein, usually medially and near field. Monitor the compressibility of both the common femoral vein, as well as the first 1-2 cm of the great saphenous vein.

 

Fig. 4: Branching of great saphenous vein (5)

CFA: common femoral artery
CFV: common femoral vein
SV: Great Saphenous Vein (5)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

b. The common femoral vein should bifurcate into the deep femoral vein, and femoral vein 1-2 cm distal to the CFV-GSV junction.  Ensure compressibility is assessed at least 1-2 cm distal to the bifurcation if the common femoral vein. Consider continuing to scan distally until the femoral vein becomes the popliteal vein or are no longer able to assess.

 

Fig.5: Femoral vein (5)

FA: Femoral Artery
FV: Femoral Vein (5)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Popliteal vein

  1. If the posterior aspect of the knee (popliteal fossa) can be easily accessed in the patient’s current position (i.e., hip externally rotated, knee slightly flexed), no further positioning changes are needed. Other options include having the patient turn to a lateral decubitus position, with the leg of interest above the other, or, have the patient sit on the side of the stretcher, with their legs dangling. (4,5)
  2. Place the probe into the posterior crease of the knee (popliteal fossa), in a transverse plane and scan 2 cm above and below to locate the popliteal vein. If the structure is not immediately identified, slide the probe slightly medially and laterally to attempt to locate it. The vein should be near field, and directly over, the popliteal artery. Once located, assess compressibility of the vessel (4,5)

 

Fig. 6: Popliteal Vein (5)

PA: Popliteal Artery
PV: Popliteal Vein (5)

Popliteal Vein compression (5)

 

 

 

 

 

 

 

 

 

 

 

 

 

Continue scanning distally (assessing compressibility along the way), until the popliteal vein trifurcates into the anterior tibial, posterior tibial, and peroneal vein. This marks the end of the examination. (4,5)

 

Fig.7: Popliteal Vein trifurcation (5)

PA: Popliteal artery
V: Popliteal Vein Trifurcation (5)

 

 

 

 

 

 

 

 

 

 

 

 

 

Doppler flow augmentation

If the veins are difficult to identify or compress, color doppler can be applied. With the probe held stationary over the vessel in question, gently squeeze the calf distal to the probe. This should augment blood flow into the vein of interest and appear (briefly) as a brighter signal. If there is no increase in blood flow seen, a DVT could be present. (3,5)

Of note, normal venous flow will also change with the respiratory cycle. As the intrabdominal pressure increases with inspiration, venous return from the lower extremities will decrease, while with expiration, flow increases. This can be appreciated with spectral doppler. (3)

 

Positive Scan

Failure to completely collapse the vein (with enough pressure to partially compress the adjacent artery), at any level, is highly suggestive for the presence of a clot.

Depending on the chronicity of the clot, it may appear echogenic enough to directly visualize under ultrasound, but this is not always the case. (3,4,5)

 

Direct clot visualization (5)

Non-compressible popliteal vein (own image)

Doppler flow around a DVT, popliteal vein (own image)

 

The Evidence

A meta-analysis published in 2019, looked at 16 articles utilizing either 2-point compression or 3-point compression and found comparable sensitivities and specificities for proximal DVT, with no statistically significant difference (1):

 

2-point compression technique

Sensitivity 91%

Specificity 98%

 

3-point compression technique

Sensitivity 90%

Specificity 95%

 

Although there was no statistically significant difference between tests, many clinicians still recommend performing the 3-point compression, to include visualization of the femoral vein.

Other studies have quoted sensitivities ranging from 93% to as high as 100% (3).

It’s important to note that compression ultrasound alone is not accurate at picking up below-knee DVT. It is rare for below-knee DVT to progress to pulmonary embolism without first extending to an above-knee DVT. Therefore, although proximal DVT is of more clinical significance in the emergency department, a negative proximal PoCUS DVT scan should be followed by a repeat scan in 5-7 days to ensure a below-knee DVT was not missed. (3)

 

Pitfalls (false positives and negatives)

False negatives

  • Small, non-occlusive DVTs may near completely compress under applied probe pressure. Ensure complete vein occlusion when applying pressure during scan.
  • Excessive probe pressure. If enough pressure is applied to compress the adjacent artery, then a DVT may also be compressed.
  • A pelvic vein DVT may be missed either due to starting the scan to distally or being unable to compress the vein due to its location. Further imaging may be required if high clinical suspicion including venography, MRI, or extended ultrasound to include the iliac vessels and IVC (3,4).

 

False positives

  • Lymph nodes can appear as non-compressible vessels. If in doubt, rotating the probe in a longitudinal orientation will reveal the spherical nature of the lymph node.
  • Superficial thrombophlebitis. These non-compressible superficial veins may be mistaken for deep veins. The major difference is superficial veins should not accompany arteries.
  • Recanalized DVT. Old thrombi that have recanalized may not compress appropriately under probe pressure, but flow should be apparent on color doppler imaging. (3,4,5)

 

Approach to DVT Diagnosis/exclusion

One in three patients with untreated DVTs will progress to clinically significant pulmonary emboli, thus diagnosis and treatment of DVT is vitally important.

Although a positive scan is very helpful, a negative scan does not rule out a thrombus, specifically a below-knee DVT, which can propagate to an above-knee DVT, and eventually a PE given time.

Multiple diagnostic approaches have been described, incorporating the DVT PoCUS scan, well established risk stratification tools (Such as Well’s criteria), and repeat imaging. Below is one such approach, adapted from Mazzolai 2017. (5,6)

 

DVT diagnostic algorithm (5)

 

Bottom Line

DVT PoCUS is a (relatively) simple scan, that can be performed quickly and used to assess for proximal DVT. Its utility is well recognized, and it is considered one of the core ultrasound applications for emergency medicine physicians by the American College of Emergency Physicians.

When assessing for DVT, the PoCUS scan should be incorporated into a diagnostic algorithm along with other risk stratification tools, and due to its low sensitivity for below-knee DVT, repeat imaging in the context of a negative scan may be warranted.

 


References

  1. Lee, J. H., Lee, S. H., & Yun, S. J. (2019). Comparison of 2-point and 3-point point-of-care ultrasound techniques for deep vein thrombosis at the Emergency Department. Medicine, 98(22).
  2. Varrias, D., Palaiodimos, L., Balasubramanian, P., Barrera, C. A., Nauka, P., Melainis, A. A., Zamora, C., Zavras, P., Napolitano, M., Gulani, P., Ntaios, G., Faillace, R. T., & Galen, B. (2021). The use of point-of-care ultrasound (Pocus) in the diagnosis of deep vein thrombosis. Journal of Clinical Medicine, 10(17), 3903.
  3. Atkinson, P., Bowra, J., Harris, T., Jarman, B., & Lewis, D. (2019). Point-of-care ultrasound for Emergency Medicine and Resuscitation. Oxford University Press
  4. Socransky, S., & Wiss, R. (2016). Essentials of point-of-care ultrasound: The ede book. The EDE 2 Course, Inc.
  5. Dinh, V. (n.d.). DVT Ultrasound made easy: Step-by-step guide. POCUS 101. Retrieved November 26, 2021, from https://www.pocus101.com/dvt-ultrasound-made-easy-step-by-step-guide/.
  6. Mazzolai, L., Aboyans, V., Ageno, W., Agnelli, G., Alatri, A., Bauersachs, R., Brekelmans, M. P., Büller, H. R., Elias, A., Farge, D., Konstantinides, S., Palareti, G., Prandoni, P., Righini, M., Torbicki, A., Vlachopoulos, C., & Brodmann, M. (2017). Diagnosis and management of acute deep vein thrombosis: A joint consensus document from the European Society of cardiology working groups of aorta and peripheral vascular diseases and pulmonary circulation and right ventricular function. European Heart Journal, 39(47), 4208–4218.
  7. Deep vein thrombosis (DVT). ACEP Symbol. (n.d.). Retrieved November 29, 2021, from https://www.acep.org/sonoguide/basic/dvt/.

 

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Advanced cardiac echo – a review of E-point septal separation

Dr. Kyle Traboulsee, PoCUS Fellow

Reviewed by Dr. David Lewis

Copyedited by Dr. Mandy Peach

Background:

Often hypotensive, or acutely dyspneic patients, present to the emergency department in significant distress, and emergency physicians must work quickly to evaluate, stabilize, and treat these patients. In the past, determining whether there was a cardiac etiology to these presentations often relied solely on history, physical exam, and varies biochemical markers. Point-of-care ultrasound has increasingly been adopted as a tool to assess cardiac function, and specifically left ventricular ejection fraction (LVEF). Different methods can be used to estimate LVEF (such as “eyeballing”, and the Simpson method), but they can have large inter-reader variability, and require significant cardiac PoCUS experience. E-point septal separation is a measurement of how close the anterior mitral valve leaflet comes towards the interventricular septum and has been shown to be a quick and easy method for estimating LVEF. (1)(2)

 

Anatomy/pathophysiology

               Blood flow is determined by pressure gradients, where blood will travel from areas of high pressure to low pressure. Such a pressure gradient exists between the left atrium and left ventricle. During diastole, the left ventricle relaxes, and the intraventricular pressure decreases until the pressure falls below that of the left intra-atrial pressure. When the left atrial pressure exceeds the left ventricular pressure, the mitral valve opens, and blood passively flows from the high(er) pressure atrium to the lower pressure ventricle. This occurs early in diastole, and the flow of blood from atrium to ventricle is further assisted by an atrial contraction (termed atrial kick) later in diastole. In a healthy individual the atrial-ventricular (A-V) gradient is sufficient to open the mitral valves and bring the anterior mitral leaflet in proximity (or contact) with the intraventricular septum. (1)(2)(3)

In the case of reduced LVEF, the diastolic pressure inside the left ventricle increases due to a decreased ability to eject blood during systole. This can occur due to several reasons, but often result in left ventricular dilation to compensate and preserve LVEF. As LVEF decreases, the ventricular diastolic pressure increases, and the atrial-ventricular (A-V) gradient decreases, leading to a decreased flow rate from atrium to ventricle during diastole, and thus a decreased mitral valve opening. That, paired with LV dilation, leads to an increased (measurable) distance between the anterior mitral valve leaflet and the intraventricular septum during diastole, which can be used as a surrogate marker for left ventricular function. (1)(2)(3).

 

PoCUS Technique

The E-point septal separation measurements will be made using a parasternal long axis (PLAX) view

Obtaining PLAX view

Steps:

  • Place probe at the left parasternal border, just caudal to manubrium (second intercostal space), perpendicular to the chest. Ensure the probe indicator is placed towards to the patient’s right shoulder.
  • Slowly slide the probe down each successive intercostal space, as well as medially (not exceeding patient midline), and laterally, until the highest quality images are obtained (this will likely be around 3-5th intercostal space, left parasternal border, but may differ from patient to patient)
  • Once the best view has been located from step 2, slowly rotate the probe to elongate the left ventricle as much as possible. The probe may need to be rocked (heeled) to center the image.

The optimal PSL image includes the left ventricle (LV) in continuity with the aortic outflow tract. The right ventricle will be near field, the left atrium far field, and the mitral valve, aortic valve, and LV cavity are in between (in the middle of the field).  The apex of the left ventricle will be screen left. (4)(5).

Parasternal long axis view- probe orientation (6)              Parasternal long axis view-anatomy (7)

Parasternal long axis view: normal (own image)

EPSS measurements

EPSS measurements are commonly obtained using M-mode.

  • Once a parasternal long axis view (PLAX) is obtained, turn on M-mode, and place the cursor over the apical tip of the anterior mitral valve leaflet.
  • The M-mode will demonstrate movement of the anterior mitral leaflet, with respect to the intraventricular septum. The image should show 2 peaks per heart cycle, under a hyperechoic line. The first, larger peak (E), represents the initial opening of the mitral valve from passive blood flow in early diastole caused by the A-V gradient. The second, usually smaller peak (A), represents the atrial kick, occurring later in diastole. This M mode image is commonly referred to as a “cloudy sky over two hills”
  • Measure the distance from the top of the E wave to the intraventricular septum. (1)(5)

A normal EPSS measurement with M-mode (8)

PSL: normal EPSS, M-mode (own image)

An abnormal EPSS measurement with M-mode (8)

EPSS measurements can alternatively be measured in B mode

  • Once a parasternal long axis view (PLAX) is obtained, ensure anterior mitral valve leaflet and septum are well visualized over 3-5 cardiac cycles
  • Freeze the image and cycle through the previous 3-5 cardiac cycles, stopping on the image where the anterior mitral valve leaflet lies closest to the intraventricular septum.
  • Measure the distance between the tip of the anterior mitral valve leaflet and the intraventricular septum.

PSL-Poor mitral valve opening (own image)

PSL view- abnormal EPSS measurement in B mode (9)

 

Interpretation

An EPSS < 7mm is considered normal

An EPSS >7 mm has been suggested as 87% sensitive and 75% specific for an EF <50% (10)

Another study suggested that an EPSS >7 mm was 100% sensitive and 51.6% specific for an EF<30% (11).

One MRI study came up with the following formula to calculate EF (4):

EF=75.5 – (2.5 x EPSS in mm)

 

Pitfalls

               Although a quick and relatively simple surrogate measurement for LVEF, there are some patient populations and situations in which EPSS may give in inaccurate estimate of cardiac function. Patients with mitral stenosis may have poor valve opening, leading to a high EPSS, in the context of an otherwise normally functioning left ventricle. Patients with aortic regurgitation may also have poor anterior mitral valve leaflet motion, and thus have a falsely high EPSS. For these reasons, it would be reasonable to apply color doppler across the mitral and aortic valves to assess for signs of regurgitant jets, as well as close assessment of the valves for signs of calcification. Off-axis measurement, regional wall motion abnormalities, and left ventricular hypertrophy may also result in false interpretations concerning LVEF (1)(3)(4).

 

Bottom line

               E-point septal separation is a relatively easy and reproducible technique that can be used to generate a quick estimation of left ventricular function and can help point towards a cardiac etiology in the undifferentiated patient.  It is important to keep in mind factors (as discussed) that may lead to false EPSS interpretations, and EPSS results should not preclude a more global cardiac assessment.

 

References:

  • Boon, S. C., Lopez Matta, J. E., Elzo Kraemer, C. V., Tuinman, P. R., & van Westerloo, D. J. (2020). POCUS series: E-point septal separation, a quick assessment of reduced left ventricular ejection fraction in a POCUS setting. Netherlands Journal of Critical Care, 28(3), 139–141.
  • Cisewski , D., & Alerhand, S. (2018, December). Fellow corner: E-point septal separation in the patient with congestive heart failure. ACEP // Home Page. Retrieved October 18, 2021, from https://www.acep.org/how-we-serve/sections/emergency-ultrasound/news/dece/fellow-corner-e-point-septal-separation-in-the-patient-with-congestive-heart-failure/.
  • Miller, T., Salerno, A., & Slagle, D. (2021, May 25). Advanced Critical Care Ultrasound: E-Point Septal Separation to Estimate Left Ventricular Ejection Fraction. EM resident . Retrieved October 2021, from https://www.emra.org/emresident/article/epss/.
  • Atkinson, P., Bowra, J., Harris, T., Jarman, B., & Lewis, D. (2019). Point-of-care ultrasound for Emergency Medicine and Resuscitation. Oxford University Press.
  • Socransky, S., & Wiss, R. (2016). Essentials of point-of-care ultrasound: The ede book. The EDE 2 Course, Inc.
  • SonoSpot, & SonoSpot. (2012, September 17). Sonotip&Trick: “I can’t get a good parasternal long view.” really? well, try this… Retrieved October 18, 2021, from https://sonospot.wordpress.com/2012/08/07/sonotiptrick-i-cant-get-a-good-parasternal-long-view-really-well-try-this/.
  • Roma, Ak, Sparks, M., Kelly, C., (@NephroP), A. K., Dowd, R., Crosson, D. A., Deepali, D., Singh, N., Andreea, Aya, S.A., A., Panchal, L. M. R., & Murthy, J. (2019, June 7). Introduction to focused cardiac ultrasound: The parasternal long axis view. Renal Fellow Network. Retrieved October 18, 2021, from https://www.renalfellow.org/2019/06/07/introduction-to-focused-cardiac-ultrasound-the-parasternal-long-axis-view/.
  • Miller, T., Salerno, A., & Slagle, D. (2021, May 25). Advanced Critical Care Ultrasound: E-Point Septal Separation to Estimate Left Ventricular Ejection Fraction. EM resident . Retrieved October 2021, from https://www.emra.org/emresident/article/epss/.
  • Satılmış Siliv, N., Yamanoglu, A., Pınar, P., Celebi Yamanoglu, N. G., Torlak, F., & Parlak, I. (2018). Estimation of cardiac systolic function based on mitral valve movements: An accurate bedside tool for emergency physicians in DYSPNEIC patients. Journal of Ultrasound in Medicine, 38(4), 1027–1038. https://doi.org/10.1002/jum.14791
  • Ahmadpour H, Shah AA, Allen JW, et al. Mitral E point septal separation: a reliable index of left ventricular performance in coronary artery disease. Am Heart J. 1983;106(1 Pt 1):21-8
  • McKaigney, C. J., Krantz, M. J., La Rocque, C. L., Hurst, N. D., Buchanan, M. S., & Kendall, J. L. (2014). E-point septal separation: A bedside tool for emergency physician assessment of left ventricular ejection fraction. The American Journal of Emergency Medicine, 32(6), 493–497. https://doi.org/10.1016/j.ajem.2014.01.045
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Rib Fractures and Serratus Anterior Plane Block

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Scaphoid Fracture – Can PoCUS disrupt the traditional ‘splint and wait’ pathway?

 

PoCUS Fellow Pearl

Dr. Melanie Leclerc, CCFP-EM

MSK PoCUS Fellow

Dalhousie University Department of Emergency Medicine

 

Reviewed & Edited by Dr David Lewis (@e_med_doc)

All case histories are illustrative and not based on any individual


 

Case:

A 37 year old, right hand dominant, carpenter presents to your local ED with a complaint of right wrist pain. He was on a step-stool and lost his balance earlier today. He fell landing on his outstretched arm and had an acute-onset of radial-sided wrist pain. He denies any other injury. There are no neurologic complaints.

On exam, there is no visible deformity. The skin is closed and there is some swelling noted. The patient is tender over the anatomic snuff box as well as volarly over the scaphoid. There is pain noted with axial loading of the thumb. There is no other tenderness. ROM is within normal limits. The limb is distally neurovascularly intact.


X-rays are normal.

An occult scaphoid fracture is suspected. At this institution, patients with suspected occult scaphoid fracture are placed in a thumb spica splint and referred to the local hand surgeon to be seen in ~10-14 days for repeat assessment and X-ray.

Can Point of Care Ultrasound change this traditional “splint and wait” patient pathway?


 

Background:

Scaphoid fracture is a common presentation to the Emergency Department accounting for approximately 15% of all wrist injuries and 70% of carpal fractures. Up to 30% of the time, radiographs at initial presentation appear normal making fracture a commonly missed injury for Emergency physicians. A failure to recognize this injury can lead to chronic pain and functional impairment for patients. Particularly, fractures of the proximal pole (most distant to the blood supply) can lead to avascular necrosis (AVN) at high rates. Non-union can lead to scaphoid non-union advanced collapse (SNAC wrist) which can perpetuate further degenerative changes throughout the carpus. This can cause a significant impact on quality of life and occupation. Early detection of fracture could expedite fixation and possibly results in better outcomes. Further study in this area is needed.


 

Anatomy:

The scaphoid bone lies in the radial aspect of the proximal carpal row. It’s unique shape (“twisted peanut”), lends to easy recognition. It articulates proximally with the distal radius, distally with the trapezium, and on its’ ulnar aspect with the lunate to form the scapho-lunate interval. The blood supply to the scaphoid is unique in that the majority of it is retrograde. The dorsal carpal branch of the radial artery supplies the bone from distal to proximal. A small proportion of the blood supply originates at the proximal end. The boundary between the two supplies creates a “watershed” area prone to non-union and AVN.


 

Classification of Fractures:

Scaphoid fractures are classified by location. These regions are the proximal, middle and distal thirds which account for 20%, 75%, and 5% of the fractures respectively. The stability of fractures is determined by the displacement (>1mm) and angulation (scapholunate angle >60 and radiolunate angle >15). The Hebert Classification as endorsed by Traumapedia can be found below.


 

Traditional Imaging:

Imaging of these suspected injuries varies. Traditionally serial X-rays were used, but have been found to be poorly sensitive even several weeks after injury. Bone scan has also been used as an alternative due to it’s high sensitivity, but has poor specificity and provides no further information regarding the nature of the fracture. CT is relatively sensitive and specific and provides information for pre-operative planning. MRI is considered the gold standard, but is difficult to obtain in a timely manner in Canada.

Bäcker HC, Wu CH, Strauch RJ. Systematic Review of Diagnosis of Clinically Suspected Scaphoid Fractures. J Wrist Surg. 2020 Feb;9(1):81-89. doi: 10.1055/s-0039-1693147. Epub 2019 Jul 21. PMID: 32025360; PMCID: PMC7000269.


 

PoCUS Technique:

  • Linear probe

  • Consider waterbath, gel standoff pad, or bag of IV fluid

  • Scan with the wrist ulnarly deviated

  • Scan in the longitudinal and transverse orientations of volar, lateral and dorsal aspects

  • Place the probe in longitudinal orientation dorsally over lister’s tubercle of the radius and scan distally until the scaphoid is visualized in the snuff box. Scan radial to ulnar.

  • Rotate to the transverse orientation and scan through proximal to distal

  • Volarly, in the transverse plane, identify the tendon of the flexor carpi radialis (this lies radial to the easily identifiable palmaris longus tendon on exam). The scaphoid is found deep to this. Scan proximal to distal.

  • Rotate to the longitudinal orientation and scan radial to ulnar

 


 

Video Demonstration:

 


 

Findings:

  • Cortical disruption

  • Periosteal elevation

  • Hematoma


 

The Evidence:

  • Early advanced imaging (CT or MRI) compared to initial 2 week immobilisation proved more cost effective and had better patient oriented outcomes (ie. missed work).(7)
  • A systematic review and meta analysis of moderate to high quality studies published in 2018 found that ultrasound had a mean sensitivity of ~89% and specificity of ~90% for detection of occult scaphoid fractures.(1)
  • Similar results were also reported by another systematic review in 2018.(8)
  • Pocus was shown to have a comparable sensitivity to CT for occult scaphoid in a systematic review published in 2020.(2)

 

Limitations:

  • Only useful if positive
  • Operator experience dependent
  • US probe and frequency dependant
  • Potential for false positives due to injury of nearby structure causing hematoma
  • Potential for false positives in context of arthritis or remote trauma

 

Bottom line:

  • Useful if positive
  • Still need definitive test to further delineate fracture (ie: for operative planning)
  • Could expedite CT
  • Could expedite specialist follow-up
  • May improve ER physician diagnostic certainty
  • May improve patient trust and compliance with splinting
  • Further study is needed

 

Case Conclusion:

Scaphoid cortical disruption was visualized using PoCUS. After discussion with the hand surgeon, a CT Scan of the wrist was performed which confirmed a minimally displaced waste fracture of the scaphoid. The patient was splinted and seen the next day in clinic for discussion regarding operative management.


 

Further Review:

 

 


 

References

  1. Ali M, Ali M, Mohamed A, Mannan S, Fallahi F. The role of ultrasonography in the diagnosis of occult scaphoid fractures J Ultrason 2018; 18: 325–331.
  2. Bäcker HC, Wu CH, Strauch RJ. Systematic Review of Diagnosis of Clinically Suspected Scaphoid Fractures. J Wrist Surg. 2020 Feb;9(1):81-89.
  3. Bakur A. Jamjoom, Tim R.C. Davis. Why scaphoid fractures are missed. A review of 52 medical negligence cases, Injury, Volume 50, Issue 7, 2019, Pages 1306-1308.
  4. Carpenter CR et al. Adult Scaphoid Fracture. Acad Emerg Med 2014; 21(2): 101-121.
  5. Gibney B, Smith B, Moughty A, Kavanagh EC, Hynes D and MacMahon PJ American Journal of Roentgenology 2019 213:5, 1117-1123
  1. Jenkins PJ, Slade K, Huntley JS, Robinson CM. A comparative analysis of the accuracy, diagnostic uncertainty and cost of imaging modalities in suspected scaphoid fractures. Injury. 2008;39:768–774.
  2. Karl, John W. MD, MPH1; Swart, Eric MD1; Strauch, Robert J. MD1 Diagnosis of Occult Scaphoid Fractures, The Journal of Bone and Joint Surgery: November 18, 2015 – Volume 97 – Issue 22 – p 1860-1868.
  3. Kwee, R.M., Kwee, T.C. Ultrasound for diagnosing radiographically occult scaphoid fracture. Skeletal Radiol 47, 1205–1212 (2018).
  4. Malahias MA, Nikolaou VS, Chytas D, Kaseta MK, Babis GC. Accuracy and Interobserver and Intraobserver Reliability of Ultrasound in the Early Diagnosis of Occult Scaphoid Fractures: Diagnostic Criteria and a Way of Interpretation. Journal of Surgical Orthopaedic Advances. 2019 ;28(1):1-9.
  5. Mallee WH, Wang J, Poolman RW, Kloen P, Maas M, de Vet HCW, Doornberg JN. Computed tomography versus magnetic resonance imaging versus bone scintigraphy for clinically suspected scaphoid fractures in patients with negative plain radiographs. Cochrane Database of Systematic Reviews 2015, Issue 6.
  6. Mallee, W.H., Mellema, J.J., Guitton, T.G. et al. 6-week radiographs unsuitable for diagnosis of suspected scaphoid fractures. Arch Orthop Trauma Surg 136, 771–778 (2016).
  7. Melville, D., Jacobson, J.A., Haase, S. et al. Ultrasound of displaced ulnar collateral ligament tears of the thumb: the Stener lesion revisited. Skeletal Radiol 42, 667–673 (2013).
  8. Meyer, P., Lintingre, P.-F., Pesquer, L., Poussange, N., Silvestre, A., & Dallaudiere, B. (2018). Imaging of Wrist Injuries: A Standardized US Examination in Daily Practice. Journal of the Belgian Society of Radiology, 102(1), 9.
  9. Mohomad et al. 2019. Accuracy of the common practice of doing X-rays after two weeks in detecting scaphoid fractures. A retrospective cohort study. Hong Kong Journal of Orthopaedic Research 2019; 2(1): 01-06.
  10. Neubauer J, Benndorf M, Ehritt-Braun C, et al. Comparison of the diagnostic accuracy of cone beam computed tomography and radiography for scaphoid fractures. Sci Rep 2018; 8:3906.
  11. Ravikant Jain, Nikhil Jain, Tanveer Sheikh, Charanjeet Yadav. 2018. Early scaphoid fractures are better diagnosed with ultrasonography than X-rays: A prospective study over 114 patients, Chinese Journal of Traumatology, Volume 21, Issue 4, Pages 206-210.
  12. Senall, JA, Failla, JM, Bouffard, JL. 2004. Ultrasound for the early diagnosis of clinically suspected scaphoid fracture. J Hand Surg Am, 29:400-405.
  13. https://essr.org/content-essr/uploads/2016/10/wrist.pdf
  14. http://www.bonetalks.com/scaphoid
  15. https://radiopaedia.org/articles/scaphoid-fracture
  16. https://sketchymedicine.com/2014/07/scaphoid-bone-anatomy-and-fractures/
  17. https://radiopaedia.org/cases/scaphoid-fracture-11?lang=gb
  18. https://www.orthobullets.com/hand/6034/scaphoid-fracture
  19. https://meeting.handsurgery.org/abstracts/2018/EP15.cgi
  20. https://www.researchgate.net/figure/Bone-scintigraphy-patient-C-of-the-hands-the-patient-with-a-scaphoid-fracture-on-the_fig4_50399987
  21. https://www.youtube.com/watch?v=7pCXiRQMRKo&t=5s&ab_channel=UltrasoundPod
  22. https://litfl.com/terry-thomas-sign
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Lisfranc Injury – We have PoCUS but do we still need the cavalry?

 

 

PoCUS Fellow Pearl

Dr. Melanie Leclerc, CCFP-EM

MSK PoCUS Fellow

Dalhousie University Department of Emergency Medicine

 

Reviewed & Edited by Dr David Lewis (@e_med_doc)

All case histories are illustrative and not based on any individual


 

Case Report

A 32 year old male presents to a rural Emergency Department with a complaint of traumatic left foot pain. He was playing recreational football this evening. While crouching, the patient was tackled by another player who landed on his hyper-plantar flexed left foot from behind. The patient had immediate onset of pain in the middle of his foot and was unable to weight-bear. 

On physical examination, you notice significant bruising and swelling of the mid-foot. There is tenderness to the medial mid-foot specifically at the 1st-2nd tarsal-metatarsal articulations. X-rays of the foot appear normal. You are concerned about the possibility of a ligamentous Lisfranc injury.

https://www.footandanklesurgery.com.au/lisfranc-injuries

 


 

Lisfranc injuries

Lisfranc injuries are those that involve the tarsal-metatarsal joints. A spectrum of injury exists from ligamentous to fracture-dislocation. Up to 20% – 40% of injuries to the Lisfranc complex are missed in the Emergency Department. Unrecognized and untreated injuries can lead to long-term instability through the midfoot. As this region of the foot is responsible for a significant load during weight bearing, instability can accelerate degenerative changes in the foot resulting in chronic pain and disability

The injury is named after Jacques Lisfranc de St. Martin, a French surgeon and gynecologist performed forefoot amputations at the tarsometatarsal joint on cavalrymen, during the 1815 Napoleonic wars. Although he didn’t specifically describe the injury, it has since been recognised in equestrians and occurring as a result of a trapped plantar flexed foot in the stirrup during a fall.

 

Other mechanisms have been described including high velocity injuries (sports injuries, foot on brake pedal MVA) and low velocity injuries (Stepping off a curb awkwardly). Low velocity injuries are more likely to be missed than high velocity injuries.

Further Reading – OrthoBullets


 

Anatomy

The Lisfranc ligament complex is comprised of 3 ligaments. The dorsal (red), interosseous (blue) and the plantar (green) Lisfranc ligaments. The  Interosseous ligament is the largest and the dorsal ligament is the smallest.

The first and second rays have unique ligamentous anatomy wherein no intermetatarsal ligaments exist, but extreme strength is imparted by dorsal, interosseous, and plantar bundles of ligament binding the lateral aspect of the medial cuneiform bone with the medial head of the second metatarsal bone—the Lisfranc ligamentous complex. Only the dorsal and plantar Lisfranc ligaments are accessible to ultrasound.

 

 



 

PoCUS of the Lisfranc joint and dorsal lisfranc ligament (DLL)

Lisfranc injuries are one of the most commonly missed orthopaedic injuries in the Emergency Department. Normal X-rays are often falsely reassuring to providers and patients are discharged with a diagnosis of “soft-tissue injury”. These injuries result in midfoot instability and often require definitive surgical management.

PoCUS has been studied as a method of early detection of these injuries. Specifically, assessment of the dorsal lisfranc ligament (DLL) between the second metatarsal (M2) and the medial cuneiform(C1). PoCUS also has the advantages of being significantly cheaper and more accessible than CT and MRI. Further investigation is needed to validate this method of diagnosis, however ultrasound findings of a disrupted DLL and a widened C1-M2 interval compared to the contralateral side may increase your suspicion when pre-test probability is high.


 

Technique

  1. Linear probe-MSK setting starting at a depth of 2cm
  2. Place probe in transverse orientation over the proximal aspect of the 1st-2nd metatarsals with the probe indicator to the patient’s right
  3. Slide the transducer proximally until you locate the medial cuneiform and identify the junction between the medial cuneiform (C1) and the 2nd metatarsal (M2)
  4. The medial cuneiform will have an angulated contour appearance in contrast to the round appearance of the metatarsals
  5. Sweep to identify the dorsal lisfranc ligament (DLL)
  6. Assess the DLL for a fibrillar pattern, normal echogenicity and contour
  7. Measure the DLL width and the C1-M2 distance compare to the contralateral side
  8. Measure the C1-M2 distance with weightbearing (if patient tolerates) to compare
  9. Apply colour doppler to assess for hyperemia


 

PoCUS Findings

Medial Cuneiform (C1), 2nd Metatarsal (M2)

Note the angulated contour of C1 and the smooth contour of M2 – this sectional plane is important when locating the dorsal Lisfranc ligament. The ligament appears hypoechoic with a fibrillar pattern, typical for other ligaments more commonly visualized with PoCUS e.g MCL, ATFL.

1. Normal image – Arrows = dorsal Lisfranc ligament

2. Normal Clip and annotated image. Note how the dorsalis pedis a. frequently overlies the dorsal Lisfranc ligament (yellow lines)

3. Normal clip. Note how there is no separation of C1/M2 while counterstressing the 1st and 2nd rays


 

4. Thickened, convex contour

5. DLL disrupted, wide joint space

6. Widening C1-M2 with weightbearing


Video Case


 

Limitations

  1. Anisotropy – Irregular dorsal contour of foot can result in difficult perpendicular imaging of doral Lisfranc ligament. Stand-off gel pad may help.
  2. History of prior trauma – chronic Lisfranc injury may result in joint widening
  3. Bilateral injuries – inability to compare sides to judge joint space widening

Application

Standard foot radiographs should be performed in all cases of suspicion for Lisfranc Injury. Weight bearing radiographs should also be performed if tolerated (the ability to fully weight bear is often limited in the acute setting)

HIgh velocity injuries result in significant soft tissue swelling, and although non-weight bearing radiographs may not be diagnostic, the index of suspicion for Lisfranc injury will be high. Immobilization +/- early CT and follow up with foot and ankle specialist is recommended. For these, high pretest probability injuries, PoCUS findings are unlikely to change management significantly. A clear Lisfranc ligament rupture on PoCUS may trigger a request for CT/MRI earlier than otherwise considered. In most cases advanced imaging and a clear diagnosis is not usually possible until the swelling has subsided.

In low velocity injuries, soft tissue swelling is less pronounced. in the acute presentation the ability to perform weight bearing radiographs is limited by pain. Index of suspicion for Lisfranc injury may be low-moderate and the decision to immobilize and refer for specialist follow up can be difficult. While there is limited published evidence for PoCUS test characteristics in Lisfranc injury, a positive scan (injury + disrupted ligament / widening of C1/M2) is likely to be highly specific. Patients with positive PoCUS findings should therefore be immobilized and referred for specialist follow up. In those with negative or inconclusive findings, management and disposition will depend on degree of clinical suspicion and correlated with radiographic findings.

In summary, PoCUS provides a useful additional piece of information that can be plugged into a bayesian diagnostic pathway. What is the pretest probability of a particular diagnosis? After reviewing radiographs and performing PoCUS is the diagnosis more or less likely?

More evidence is required to fully understand the test characteristics of PoCUS for Lisfranc injury. Would the addition of plantar views improve sensitivity?

Although the performing the scan takes only a few minutes, it is quite technically challenging for the novice. As with all MSK PoCUS, repeated practice in numerous patient presentations will increase operator speed and accuracy.


 

Finally, although we still need the cavalry, PoCUS can help us decide which regiment and how quickly we need them!

 


References

  1. Mayich DJ, Mayich MS, Daniels TR. Effective detection and management of low-velocity Lisfranc injuries in the emergency setting: principles for a subtle and commonly missed entity. Can Fam Physician. 2012;58(11):1199-e625. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3498011
  2. Woodward, S., Jacobson, J.A., Femino, J.E., Morag, Y., Fessell, D.P. and Dong, Q. (2009), Sonographic Evaluation of Lisfranc Ligament Injuries. Journal of Ultrasound in Medicine, 28: 351-357.
  3. Döring, S., Provyn, S., Marcelis, S., Shahabpour, M., Boulet, C., de Mey, J., De Smet, A., De Maeseneer, M. (2018). Ankle and midfoot ligaments: Ultrasound with anatomical correlation: A review. Eur J Radiol.107:216-226.
  4. Kaicker, J., Zajac, M., Shergill, R., & Choudur, H. N. (2016). Ultrasound appearance of the normal Lisfranc ligament. Emergency Radiology, 23(6), 609-614.
  5. DeLuca, M.K., Walrod, B. and Boucher, L.C. (2020). Ultrasound as a Diagnostic Tool in the Assessment of Lisfranc Joint Injuries. J Ultrasound Med, 39: 579-587.
  6. Marshall, J., Graves, N.C., Rettedal, D.D., Frush, K., Vardaxis. V. (2013). Ultrasound Assessment of Bilateral Symmetry in Dorsal Lisfranc Ligament. The Journal of Foot and Ankle Surgery, 52(3): 319-323.
  7. Rettedal, D.D., Graves, N.C., Marshall, J.J. et al. Reliability of ultrasound imaging in the assessment of the dorsal Lisfranc ligament. J Foot Ankle Res 6, 7 (2013).
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Detection of Foreign Bodies in Soft Tissue – A PoCUS-Guided Approach

 

Medical Student Clinical Pearl

Sophia Miao, CC4

MD Candidate, Class of 2021

Dalhousie University

 

Reviewed & Edited by Dr David Lewis (@e_med_doc)

All case histories are illustrative and not based on any individual.


 

Case Report

A 33-year-old woman presents to the ED with pain and swelling over the third digit of her right hand.  One week prior to this, she had shattered a jar and a small glass splinter lodged into her finger.  This was promptly removed at home, and the puncture wound healed without intervention.

She presented to the emergency room 7 days later with new pain and swelling surrounding the initial puncture wound.  There is no significant past medical history and most recent Td booster was given 2 years ago.  On examination, there was some mild erythema, swelling, and tenderness on palpation of the lateral aspect of the middle phalanx of the right hand.  She is otherwise well.  You wonder about the possibility of a retained foreign body.


 

PoCUS-Guided Approach to the Detection of Foreign Bodies in Soft Tissue

Foreign bodies in soft tissue are a common complaint in the emergency department, with open wounds comprising 5.7 million (or 4.5% of total) visits to the ED in 2010.[1]  Foreign bodies were found in up to 15% of wounds.[2]  If retained, complications of these include allergic reaction, inflammation, delayed wound healing, damage to adjacent tissue structures, neurovascular damage, tetanus, and infectious complications including cellulitis, necrotizing fasciitis, synovitis, and abscess formation.[3],[4]  Proper detection, and subsequent removal, of retained foreign bodies is therefore essential to evaluate the wound and prevent associated complications.

Diagnosis of a retained FB requires a high index of suspicion.  Clinical suspicion should be raised when there is a compelling history and physical exam.  The latter may include signs of inflammation and/or infection, including warmth, swelling, erythema, tenderness, abscess formation, and discharging wound).[5],[6]

Conventional radiography is known to commonly miss radiolucent materials such as wood and plastic.  It has been shown that plain radiographs have only a 7.4% sensitivity in the detection of wood foreign bodies.5  Remarkably, even glass – a radiopaque material – has been demonstrated to have been missed in up to 35% of x-ray film studies.[7]  There is increasingly compelling evidence for the clinical usefulness and accuracy of bedside ultrasonography in the detection of soft-tissue foreign bodies.  It has been shown to have a specificity of 92% (95% CI = 88%-95%) and sensitivity ranging from 83.3% to 100%.[8],[9]


PoCUS Technique

Probe selection: the use of a high-frequency ultrasound probe is recommended.  This allows for greater axial resolution at the expense of less penetration, which is suitable for the detection of small foreign bodies, as they typically lodge in superficial tissues.[10]

If the wound is open, a transparent covering such as a Tegaderm or probe cover can be used to cover either the wound or probe before scanning.[11]

Medium: standard technique for assessment of soft-tissue structures by ultrasound involves the use of a standoff pad or gel mound.  However, this is not always possible due to the irregular curvature of extremities such as fingers and feet, which may result in poor contact between the probe and skin, decreased field of view, and patient discomfort.  A water-bath technique can circumvent this and has been shown to be superior in such cases.[12]

Method: the area of interest should be scanned in both longitudinal and transverse planes.  Foreign bodies are best detected when the transducer aligns with the longitudinal axis of the foreign body, and therefore revealing the span of the object.[13]  As foreign bodies tend to embed less than 2 cm below the surface of the skin, the depth of field should remain superficial in order to avoid false positives.

US Probe: Ultrasound Water Bath for Distal Extremity Evaluation

 


Findings

Ultrasonography and plain film findings of foreign bodies in soft tissue are summarized in the table below.

Table 1. Ultrasound and x-ray findings of foreign bodies.6,[14],[15],[16]

Material Ultrasound findings X-ray findings
Wood Hyperechoic; may become isoechoic with surrounding tissue as it denatures over time

Posterior acoustic shadowing

Radiolucent, often undetectable
Glass Hyperechoic, bright

Posterior acoustic shadowing

± Posterior comet tail reverberation, diffuse beam scattering

Radiopaque
Plastic Hyperechoic

Posterior acoustic shadowing

Radiolucent, often undetectable
Metal Hyperechoic, bright

Posterior acoustic shadowing

± Posterior comet tail reverberation

Radiopaque

 

Foreign bodies may also display a straight or regular contour.6

 

Image 1 – Wood splinter in volar aspect digit, mildly hyperechoic, surrounding hypoechoic halo, irregular acoustic shadowing

Image 2 – Plastic FB, within tendon sheath, volar aspect digit, brightly hyperechoic, long axis

Image 3 – Plastic FB, within tendon sheath, volar aspect digit, brightly hyperechoic, short axis

 

Image 4 – Glass FB – brightly echogenic, posterior reverberation, FB long axis

 

Image 5 – Metal FB – brightly echogenic, posterior reverberation, FB long axis

 

 

It is important to note that the acoustic shadowing may be complete or partial, as this is dependent on the angle of sonography and foreign body material.[17]  It is also possible to see a hypoechoic halo around the FB, which may be suggest edema, abscess formation, granulation tissue, or other inflammatory process.[18]  As the inflammatory reaction develops, the halo effect becomes more apparent; therefore the foreign body is therefore best visualized by PoCUS several days after the initial injury.6


PoCUS-Guided Foreign Body Removal

There are several options for removal of a foreign body with PoCUS:[19]

  1. Needle localization. Once the foreign body has been identified on PoCUS, a hollow injection needle can be inserted under ultrasound guidance and local anesthetic is delivered through this.  This can be done in either the transverse or longitudinal plane.  The ultrasound probe is then removed, and an incision is made along the needle.  Through the incision site, tweezers or forceps can be used to remove the foreign body.
  2. Real-time ultrasound-guided extraction. This technique is similar to the needle localization method. However, rather than removing the transducer following the needle insertion, the entire procedure is done under direct ultrasound visualization.  The probe is held in the longitudinal plane to visualize both the forceps and the foreign body during the extraction process.

 

There is a risk of obscuring the view of the foreign body on ultrasound with air as a result of the incision itself or through anesthetic delivery.  Saline may be used to irrigate and therefore mitigate the issue.19

The patient’s tetanus status should be verified and updated, if required.  Antibiotic therapy may also be provided, should the risk of infection justify it.


Limitations

There is the possibility of false positives.  Foreign bodies must be differentiated from other hyperechoic body structures, including ossified cartilage, sesamoid bones, scar tissue, gas bubbles, and intermuscular fascia.14  Visualization is therefore important in both longitudinal and transverse planes, as well as comparison with the opposite side.  Acoustic shadowing, hypoechoic halo, and posterior comet tails, if present, can also be indicative of a FB rather than organic body tissue.

Traumatic air injection as a result of penetrating injury can create a scatter artifact on ultrasound, which can be misinterpreted as an acoustic shadow associated with a foreign body.  To differentiate this from a true acoustic shadow, pressure may be applied through the transducer to displace the scatter artifact.6

As is commonplace with all emergency ultrasonography, limitations also include the technical skill of the operator.[20]  A foreign body may also be too small to be detectable by ultrasound.  It is therefore important to remember that a negative scan does not necessarily rule out the possibility of a retained foreign body, and the history and physical examination must be considered in conjunction with the ultrasound findings.

 


 

References

[1] National Center for Health Statistics. Emergency Department Visits. Available from: http://www.cdc.gov/nchs/fastats/emergency-department.htm.

[2] Steele MT, Tran LV, Watson WA, Muelleman RL. Retained glass foreign bodies in wounds: predictive value of wound characteristics, patient perception, and wound exploration. Am J Emerg Med. 1998 Nov;16(7):627-30. DOI: 10.1016/s0735-6757(98)90161-9. PMID: 9827733.

[3] Skinner EJ, Morrison CA. Wound Foreign Body Removal. In:StatPearls. Treasure Island (FL): StatPearls Publishing; 2020. Available from: https://www.ncbi.nlm.nih.gov/books/NBK554447/.

[4] Ebrahimi A, Radmanesh M, Rabiei S, Kavoussi H. Surgical removal of neglected soft tissue foreign bodies by needle-guided technique. Iran J Otorhinolaryngol. 2013 Winter;25(70):29-36. PMID: 24303416; PMCID: PMC3846242.

[5] Levine MR, Gorman SM, Young CF, Courtney DM. Clinical characteristics and management of wound foreign bodies in the ED. Am J Emerg Med. 2008 Oct;26(8):918-22. DOI: 10.1016/j.ajem.2007.11.026. PMID: 18926353.

[6] Atkinson P, Bowra J, Harris T, Jarman B, Lewis D. Point of Care Ultrasound for Emergency Medicine and Resuscitation. Oxford, United Kingdom: Oxford University Press; 2019. DOI: 10.1093/med/9780198777540.001.0001.

[7] Kaiser, C. William MD; Slowick, Timothy MBA; Spurling, Kathleen Pfeifer RN, JD; Friedman, Sissie MA. Retained Foreign Bodies, The Journal of Trauma: Injury, Infection, and Critical Care: July 1997 – Volume 43 – Issue 1 – p 107-111.

[8] Davis J, Czerniski B, Au A, Adhikari S, Farrell I, Fields JM. Diagnostic Accuracy of Ultrasonography in Retained Soft Tissue Foreign Bodies: A Systematic Review and Meta-analysis. Acad Emerg Med. 2015 Jul;22(7):777-87. DOI: 10.1111/acem.12714. Epub 2015 Jun 25. PMID: 26111545.

[9] Atkinson P, Madan R, Kendall R, Fraser J, Lewis D. Detection of soft tissue foreign bodies by nurse practitioner-performed ultrasound. Crit Ultrasound J. 2014 Jan 29;6(1):2. DOI: 10.1186/2036-7902-6-2. PMID: 24476553; PMCID: PMC3922659.

[10] Dean AJ, Gronczewski CA, Costantino TG. Technique for emergency medicine bedside ultrasound identification of a radiolucent foreign body. The Journal of Emergency Medicine. 2003;24(3):303–8. DOI: 10.1016/S0736-4679(02)00765-5.

[11] Chen KC, Lin AC, Chong CF, Wang TL. An overview of point-of-care ultrasound for soft tissue and musculoskeletal applications in the emergency department. J Intensive Care. 2016 Aug 15;4:55. DOI: 10.1186/s40560-016-0173-0. PMID: 27529031; PMCID: PMC4983782.

[12] Krishnamurthy R, Yoo JH, Thapa M, Callahan MJ. Water-bath method for sonographic evaluation of superficial structures of the extremities in children. Pediatr Radiol. 2013 Mar;43 Suppl 1:S41-7. DOI: 10.1007/s00247-012-2592-y. Epub 2013 Mar 12. PMID: 23478918.

[13] Rooks VJ, Shiels WE 3rd, Murakami JW. Soft tissue foreign bodies: A training manual for sonographic diagnosis and guided removal. J Clin Ultrasound. 2020 Jul;48(6):330-336. DOI: 10.1002/jcu.22856. Epub 2020 May 8. PMID: 32385865.

[14] Mohammadi A, Ghasemi-Rad M, Khodabakhsh M. Non-opaque soft tissue foreign body: sonographic findings. BMC Med Imaging. 2011 Apr 10;11:9. DOI: 10.1186/1471-2342-11-9. PMID: 21477360; PMCID: PMC3079678.

[15] Lewis D, Jivraj A, Atkinson P, Jarman R. My patient is injured: identifying foreign bodies with ultrasound. Ultrasound. 2015 Aug;23(3):174-80. DOI: 10.1177/1742271X15579950. Epub 2015 Mar 26. PMID: 27433254; PMCID: PMC4760591.

[16] Campbell EA, Wilbert CD. Foreign Body Imaging. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020. Available from: https://www.ncbi.nlm.nih.gov/books/NBK470294/.

[17] Anderson MA, Newmeyer WL 3rd, Kilgore ES Jr. Diagnosis and treatment of retained foreign bodies in the hand. Am J Surg. 1982 Jul;144(1):63-7. DOI: 10.1016/0002-9610(82)90603-1. PMID: 7091533.

[18] Little CM, Parker MG, Callowich MC, Sartori JC. The ultrasonic detection of soft tissue foreign bodies. Invest Radiol. 1986 Mar;21(3):275-7. DOI: 10.1097/00004424-198603000-00014. PMID: 3514541.

[19] Paziana K, Fields JM, Rotte M, Au A, Ku B. Soft tissue foreign body removal technique using portable ultrasonography. Wilderness Environ Med. 2012 Dec;23(4):343-8. DOI: 10.1016/j.wem.2012.04.006. Epub 2012 Jul 25. PMID: 22835803.

[20] Pinto A, Pinto F, Faggian A, Rubini G, Caranci F, Macarini L, Genovese EA, Brunese L. Sources of error in emergency ultrasonography. Crit Ultrasound J. 2013 Jul 15;5 Suppl 1(Suppl 1):S1. DOI: 10.1186/2036-7902-5-S1-S1. Epub 2013 Jul 15. PMID: 23902656; PMCID: PMC3711733.

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A Case of Ectopic Pregnancy

 

Medical Student Clinical Pearl – December 2020

Marisa O’Brien

@mbob58

MD Candidate, Class of 2021

Memorial University of Newfoundland

Reviewed and Edited by Dr. David Lewis

All case histories are illustrative and not based on any individual

 


Case Report

A 36-year-old G2P1 female presented to the Emergency Department following a pre-syncopal episode at work. The patient noted a sudden onset of significant abdominal cramping, nausea, and vaginal bleeding with clots that morning followed by an episode of lightheadedness while sitting at her desk. The patient denied any loss of consciousness, no dyspnea, no chest pain, no palpitations, and no fevers/chills. She had no known allergies and no current medications. She was a non-smoker and denied any alcohol or drug usage.

The patient’s past medical history was significant for recent treatment with methotrexate for an ectopic pregnancy eight days prior. The patient had a history of amenorrhea for 7 weeks and a serum β-hCG of 302 mlU/mL at that time. A transvaginal ultrasound was performed at 8 weeks for abdominal pain and light spotting which revealed an IUD in situ with no evidence of an intrauterine pregnancy. An early ectopic pregnancy was diagnosed and the patient was consented to receive medical management with methotrexate. She was followed up with serial β-hCG’s which gradually, but slowly, trended down to 110 mIU/ml by day 6. The patient noted slight abdominal cramping and PV bleeding following the methotrexate however this had settled after 3 days with no ongoing symptoms until today.

On initial assessment, the patient appeared well, no acute distress, and all vital signs were stable.  The abdominal exam revealed bowel sounds present in all four quadrants and the abdomen was tympanic to percussion. On palpation the abdomen was soft and nondistended with LLQ and suprapubic tenderness however, no guarding or rebound tenderness was appreciated.

Initial investigations included a CBC, β-hCG, PT & PTT, type and screen, urinalysis, EKG, & POCUS.

 


Definition

An ectopic pregnancy occurs when a fertilized egg implants at a site other then the endometrium of the uterus, most commonly the fallopian tubes. They often present as vaginal bleeding and/or abdominal pain in the setting of a positive β-hCG.1

A critical complication is a ruptured ectopic pregnancy which occurs by erosion through the tissue the zygote has implanted in resulting in intraabdominal bleeding from the exposed vessel and possible hypovolemic shock.2 Rupture should be suspected in patients presenting with hemodynamic instability including syncope, hypotension, and tachycardia. However, young healthy females may appear vitally stable initially due to compensatory mechanisms. Additional physical exam findings suggestive of a ruptured ectopic pregnancy include severe abdominal pain with guarding or rebound tenderness and abdominal distention. Pain may radiate to the shoulder due to irritation of the diaphragm from blood in the peritoneal cavity.1,3

 


Risk factors for ectopic pregnancy4

  • Previous ectopic pregnancy
  • Prior fallopian tube surgery
  • Previous pelvic or abdominal surgery
  • Sexually transmitted infections
  • Pelvic inflammatory disease
  • Endometriosis
  • Cigarette smoking
  • Maternal age > 35 years
  • History of infertility
  • Assisted reproductive technology (IVF)

 

 


Differential diagnosis for vaginal bleeding in early pregnancy1:

  • Physiologic
  • Spontaneous abortion
  • Cervical, vaginal, or uterine pathology
  • Subchorionic hematoma
  • Heterotopic pregnancy
  • Gestational trophoblastic disease

 


Sonography

According to the discriminatory zones, an intrauterine pregnancy is expected to be visualized on a transvaginal ultrasound at β-hCG levels of 1500 – 2000 mlU/mL and on a transabdominal ultrasound at levels of 4000 – 6500 mlU/mL.5

Gestational Age Β-hCG range (mlU/mL)
<1 week 5 – 50
1-2 weeks 50 – 500
2-3 weeks 100 – 5000
3-4 weeks 500 – 10,000
4-5 weeks 1000 – 50,000
5-6 weeks 10,000 – 100,000
6-8 weeks 15,000 – 200,000
8-12 weeks 10,000 – 100,000

Table 1: Estimated β-hCG levels in relation to gestational age.3

In the first trimester of a normal pregnancy, the serum β-hCG should increase by ≥ 53% every 48 hrs until 41 days of gestation.1,3 Serum β-hCG will then continue to rise more slowly until approximately 10 weeks after which it will begin to decline until reaching a plateau. Serum β-hCG levels are noted to raise more slowly in an ectopic pregnancy, thus a slower rate of increase, plateau, or decline in serum β-hCG in the first 41 days suggests a possible miscarriage or ectopic pregnancy.1

Note on β-hCG Discriminatory Zones

The value of discriminatory zones in the emergency management of ectopic pregnancy is low, with many considering it unreliable and potentially dangerous. In short, a low β-hCG does not exclude an ectopic. This useful post provides a good summary on ectopic rule-out in the ED:

Rule Out Ectopic in the Emergency Department

 

An intrauterine pregnancy is confirmed by visualization of a gestational sac and a yolk sac within the uterus (juxtaposed to bladder).1 A gestational sac alone is not sufficient for diagnoses of an intrauterine pregnancy as it may be a pseudogestational sac formed by hormonal stimulation from an ectopic pregnancy.5 Additionally, if an intrauterine pregnancy is visualized, a heterotopic pregnancy should also be considered.1 The risk of heterotopic pregnancy when conceived normally is estimated to be 1 in 30,000.

Figure 1: Visualization of an intrauterine pregnancy on a transvaginal ultrasound.3

 

 

Structure Transvaginal Ultrasound Transabdominal Ultrasound
Gestational Sac 4.5-5 weeks 5.5-6 weeks
Yolk Sac 5-5.5 weeks 6-6.5 weeks
Fetal Pole 5.5-6 weeks 7 weeks
Cardiac Activity 6 weeks 7 weeks
Fetal Parts 8 weeks >8 weeks

Table 2: Ultrasound findings based on gestational age.5

 


Diagnosis of Ectopic Pregnancy

An ectopic pregnancy is suspected in all women with a positive pregnancy test when no intrauterine pregnancy is visualized on ultrasonography. A low β-hCG or declining β-hCG does not exclude an ectopic. Ultrasound findings of an ectopic pregnancy may include an extrauterine gestational sac or embryonic cardiac activity outside of the uterus, a complex adnexal mass, or intraperitoneal fluid.3

From emupdates.com

 


Management of Ectopic Pregnancy

Is the patient unstable?

  • If the patient is hemodynamically unstable (tachycardia or hypotension or pale or syncopal) then commence immediate resuscitation (IV Access, CBC, type & crossmatch,  iv fluids, transfusion, etc) and stat consult to ObGyn.

In stable patients

  • Consult ObGyn
  • The gold-standard of treatment for ectopic pregnancy is surgical management however, treatment options include expectant, or medical management.6 Medical management with methotrexate, a folic acid antagonist that inhibits DNA synthesis and cell production, has a higher success rate when initiated at lower β-hCG levels. Methotraxate is initiated if β-hCG is <5000 mlU/mL and is reserved for those with reliable follow up as β-hCG levels are required to be trended until they are undetectable. Individuals with renal disease, hepatic disease, active pulmonary disease, or immunodeficiencies are not candidates for methotrexate.3,7 Individuals who do not meet the criteria for medical management, are hemodynamically unstable, have failed methotrexate, or a ruptured ectopic is suspected, will receive surgical management.6

 


Case Report Continued

The patient was hemodynamically stable on presentation. Her vital signs were normal. As part of the initial assessment, PoCUS was used to further evaluate for the presence of free fluid in the abdomen or pelvis. Free fluid was identified in the RUQ in both Morrison’s pouch and surrounding the caudal tip of the liver. Intraperitoneal fluid was also seen in the LUQ in both the subphrenic and splenorenal spaces. Free fluid was also visualized in Douglas’ pouch in the pelvic view.

RUQ

LUQ

Pelvis

 

Throughout the PoCUS examination the patient remained well appearing, however she had become hypotensive with a blood pressure of 90/53 mmHg. Her initial bloodwork had come back at this time revealing a β-hCG of 32 mlU/mL and a Hgb of 67 g/L. The patient received 1g of TXA, and a 1L bolus of normal saline while PRBC’s were ordered. She was documented to be Rh+ thus, she did not require RhoGAM (anti-D immune globulin). An urgent consultation to Obstetrics and Gynecology was made following the visualization of intraabdominal fluid and the patient underwent an exploratory laparotomy shortly after.

 


Key Points

  • Ectopic pregnancy should be considered in the differential diagnosis of any female patient, of childbearing age, presenting with abdominal pain, syncope or shock
  • An Intrauterine contraceptive device does not exclude an ectopic
  • Unless a previous ultrasound has documented the presence of an intrauterine pregnancy, an empty uterus in a patient with a positive pregnancy test should be considered to be a possible ectopic until ruled out
  • An intrauterine pregnancy on ultrasound requires the following to be confirmed:
    • A gestational sac and a yolk sac, in the uterus which is juxtaposed to the bladder
    • or a gestational sac containing a normal fetal pole, in the uterus which is juxtaposed to the bladder
  • A low β-hCG or declining β-hCG does not exclude an ectopic
  • Medical management of ectopic pregnancy with methotrexate requires close follow-up. Failure can occur. Ruptured ectopic pregnancy can still occur.

 


Further Reading

Ectopic Pregnancy and Ruptured Ectopic: Pitfalls in Diagnosis

ED Rounds – Early Pregnancy

The Pregnant ED Patient – A Compendium of Pearls

 

 


References

  1. Tulandi, T. (2020, November 2). Ectopic pregnancy: Clinical manifestations and diagnosis. Retrieved from: https://www.uptodate.com/contents/ectopic-pregnancy-clinical-manifestations-and-diagnosis?search=ectopic%20pregnancy&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1#H1
  2. Toy, E.C., Simon, B.C., Takenaka, K.Y., Liu, T.H., & Rosh, A.J. (2017). Ectopic Pregnancy. Case Files Emergency Medicine. (4th, pp. 369-376). McGraw-Hill Education.
  3. Hang, B.S. (2016). Obstetrics and Gynecology. Tintinalli’s Emergency Medicine: A Comprehensive Guide. (8th, pp. 629-633). McGraw-Hill Education.
  4. The American College of Obstetricians and Gynecologists. (2018, February). Retrieved from: https://www.acog.org/womens-health/faqs/ectopic-pregnancy
  5. Leonard, N.J. (2019, January 23). The Pregnant Pelvic POCUS. EMRounds. Retrieved from: https://emrounds.org/the-pregnant-pelvic-pocus/
  6. Tulandi, T. (2020, March 31). Ectopic pregnancy: Choosing a treatment. Retrieved from: https://www.uptodate.com/contents/ectopic-pregnancy-choosing-a-treatment?search=ectopic%20pregnancy&topicRef=5407&source=see_link#H2976630177
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Small Bowel Obstruction & PoCUS

Small Bowel Obstruction & PoCUS – Medical Student Pearl

Patrick Rogers, Clinical Clerk (CC3)

Memorial University of Medicine Class of 2021

Reviewed by Dr. Kavish Chandra

Small bowel obstructions (SBO) are a common cause of acute abdominal pain in emergency departments across Canada. Diagnostic imaging plays a key role in the diagnosis and management of SBO as the history, clinical examination and laboratory investigations lack the sensitivity and specificity needed. Furthermore, diagnostic imaging may help differentiate SBO from other causes of abdominal pain (hernias, malignancies, intussusception, etc).

Historically, plain film abdominal radiography (AXR) has been an initial investigation in emergency departments when an SBO is suspected.  However, the current literature suggests that abdominal radiography is a relatively poor test for the diagnosis or exclusion of SBO when compared to other available modalities like US, CT, or MRI. In fact, multiple studies argue for the reduction of abdominal x-rays, especially when patients come in presenting with general abdominal tenderness. 1 Fortunately, there exists a compelling alternative: point of care ultrasound (PoCUS), and is being increasingly used as a first line investigation for SBO. 2

There are several reasons why physicians may start to choose PoCUS over traditional diagnostic modalities:

  • PoCUS avoids the radiation exposure that patients receive from cumulative plain films and abdominal CT’s. 3
  • PoCUS has been shown to reduce time to diagnosis and treatment in comparison to abdominal plain films. 3
  • PoCUS is more sensitive/specific modality when compared to abdominal plain film. 4
  • PoCUS allows for serial examination in the ED. 5
  • PoCUS may be rapidly available to centers with limited access to CT scanner. 6

The current evidence is highly favorable for the diagnostic efficacy of PoCUS in SBO. Here are the findings of peer-reviewed studies on the subject (published between 2013-2020):

  • PoCUS has high diagnostic accuracy and may also decrease time to diagnosis of SBO in comparison to other imaging modalities like CT and plain film.2
  • PoCUS has been found to have superior diagnostic accuracy for SBO in comparison to plain abdominal radiography. 4
  • PoCUS has been shown to be an accurate tool in the diagnosis of SBO with a consistently high sensitivity of 94-100% and specificity of 81-100%. 5
  • Current evidence suggests PoCUS is comparable in sensitivity and specificity to a CT scan when diagnosing SBO. 6
  • Ultrasound was found to be equivalent to CT in terms of diagnostic accuracy with a sensitivity of 92.31% (95% CI, 74.87% to 99.05%) and a specificity of 94.12% (95% CI, 71.31% to 99.85%) in the diagnosis of SBO. 7
  • In a study comparing XR, US, CT, and MRI, the abdominal x-ray was shown to be to be the least accurate imaging modality for the diagnosis of SBO. AXR’s were found to have a positive likelihood ratio of 1.64 (95% CI 1.07 to 2.52). In contrast, CT and MRI were both quite accurate in diagnosing SBO with positive likelihood ratios of 3.6 (95% CI = 2.3 to 5.4) and 6.77 (95% CI = 2.13 to 21.55). The use of ultrasound was found to have a positive likelihood ratio of 9.55 (95% CI = 2.16 to 42.21) and a negative likelihood ratio of 0.04 (95% CI = 0.01 to 0.13) for beside scans. 4

There are two major barriers identified in the literature that may prevent the effective use of PoCUS in the diagnosis of SBO. First, not every emergency physician has been trained on the use of PoCUS. Fortunately, two recent studies show that even minimally trained ED physicians can use it accurately. 8 Secondly, some surgeons have argued that PoCUS does not show the location of the obstruction accurately. This becomes a concern when the care team elects for surgical management of the patient’s SBO. However, recent evidence suggests that PoCUS may lead to quicker time to diagnosis and enteric tube insertion in conservative management. 8

Finally, how can learners use this technology? 5 Here are some specific sonographic findings to look for when evaluating a patient for SBO with US:

 

  • Dilatation of small bowel loops > 25 mm *
  • Altered intestinal peristalsis *
  • Increased thickness of the bowel wall
  • Intraperitoneal fluid accumulation

Figure 1. Dilatation of small bowel loops. Image courtesy Dr. Kavish Chandra

Figure 2. Altered intestinal peristalsis*. Image courtesy Dr. Kavish Chandra

Figure 3. – abnormal peristalsis “to and fro”9

References

  1. Denham G, Smith T, Daphne J, Sharmaine M, Evans T. 2020. Exploring the evidence-practice gap in the use of plain radiography for acute abdominal pain and intestinal obstruction: a systematic review and meta-analysis. International Journal of Evidence Based Healthcare. DOI: 10.1097/XEB.0000000000000218
  2. Guttman J, Stone M, Kimberly H, Rempell J. 2015. Point of care ultrasonography for the diagnosis of small bowel obstruction in the emergency department. CJEM. DOI: 10.2310/8000.2014.141382
  3. Flemming H, Lewis D. 2016. SBO- A New Focus for PoCUS. Saint John Regional Hospital Department of Emergency Medicine
  4. Taylor M, Lalani N. 2013. Adult small bowel obstruction. Academic Emergency Medicine. DOI: 10.1111/acem.12150
  5. Pourman A, Dimbil U, Shokoohi H. 2018. The accuracy of point of care ultrasound in detecting small bowel obstruction in emergency department. Emergency Medicine International. DOI: 10.1155/2018/3684081
  6. Gottlieb M, Peska, G, Pandurangadu A, Nakitende D, Takhar S, Seethala R. 2018. Utilization of ultrasound for the evaluation of small bowel obstruction: A systematic review and meta-analysis. The American Journal of Emergency Medicine. DOI: 10.1016/j.ajem.2017.07.085
  7. Tamburrini S, etal. 2019. Diagnostic accuracy of ultrasound in the diagnosis of small bowel obstruction. Diagnostics. DOI: 10.3390/diagnostics9030088
  8. Carpenter C. 2013. The end of X-Rays for suspected small bowel obstruction? Using evidence-based diagnostics to inform best practices in emergency medicine. Academic Emergency Medicine. https://doi.org/10.1111/acem.12143
  9. The PoCUS Atlas. https://www.thepocusatlas.com/bowel-gi

Copyedited by Dr. Mandy Peach

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Skin and Soft Tissue Infections: A PoCUS Guided Approach

Medical Student Clinical Pearl – November 2020

 

Robert Hanlon

@roberthanlon12

Year: 4
DMNB Class of 2021
 

Reviewed and Edited by Dr. David Lewis

All case histories are illustrative and not based on any individual

 


Case Report

A 25yr old male presents with a 3 day history of a red swollen foot following an insect bite. He has no past medical history. On examination there is some erythema and swelling on the dorsum of the left foot. Palpation is very tender.

You are aware of recommended guidelines that advise I&D for purulent infections and decide to proceed with the procedure. Despite trying to freeze the area with lidocaine, the procedure is still painful and no pus is drained. You point to the minimal serosanguinous exudate and sheepishly suggest to the patient that the I&D was successful and that a course of antibiotics will resolve this issue.


Skin and Soft Tissue Infections: A POCUS Guided Approach

Skin and soft tissue infections (SSTIs) have a variety of potential causes, ranging in severity from mild infections like cellulitis to abscess all the way to life-threatening causes like necrotizing fasciitis.1 SSTIs are commonly encountered in the emergency department, with cellulitis and abscesses being the two most common.2 It is important to be able to recognize SSTIs and provide appropriate treatment. Abscesses require invasive management, whereas cellulitis is treated with systemic therapies; therefore, it is important to be able distinguish the different between the two types. Doing so can be difficult because of the hidden nature of abscesses. However, ultrasound can be a useful tool in establishing the presence of an abscess. This article is a review of the clinical approach and treatment for SSTIs, focusing on cellulitis and abscesses, as well as the use of ultrasound in helping to establish the diagnosis.


Approach

Clinical suspicion is the initial step in the diagnosis of SSTIs. These infections have multiple causes; therefore, obtaining a detailed history is crucial. Information about immunocompromised state, place of residence, travel, any recent trauma or surgery, previous antimicrobial use, lifestyle, hobbies, and animal bites is essential to developing an adequate differential diagnosis.3

A good understanding of the normal skin flora and common infectious organisms is key to assessing SSTIs. The most commons organisms implicated in SSTIs are Staphylococcus aureus and Streptococcus species.4-6 Methicillin resistant S. aureus (MRSA) being an important strain that has increased in prevalence in the past 20 years. Risk factors such as presence of abscess, intravenous drug use, previous MRSA status, antibiotics within 8 weeks, diabetes mellitus, and previous hospital admission within the last year increase the likelihood of the infection being cause by MRSA.4-6

Physical examination findings are crucial for establishing the presence of an SSTI; the typical criteria are a superficial lesion with the classic inflammatory findings of redness (rubor), swelling (tumor), warmth (calor), and pain (dolor).1,2,7 An abscess is defined as a fluctuant mass of puss localized and buried within a tissue, organ, or potential space; however, clinically it can be hard to determine to presence of this mass.2,7 Other associated signs and symptoms, such as crepitus, bullae, and hemorrhage, may be present upon diagnosis or may develop later during the course.2,7 Due to overlapping clinical presentations of the different SSTIs, it can be difficult to differentiate between them.


Cellulitis – No Abscess
Cellulitis – Possible Abscess
Abscess
Early Abscess

Assessment with POCUS:

Due to the similarities between different SSTI cutaneous findings and their different treatments, it is important to establish if there is an abscess present. It was common, before the introduction of ultrasound, to perform a blind needle aspiration of the infected area in order to determine the presence/absence of an abscess.8,9 However, this subjects that patient to the risks of an invasive procedure as well as pain. On the other hand, treating infection with empiric antibiotics in the presence of an unknown abscess delays drainage and allows for potential worsening of the infection.8,9

A study by Tayal et al. demonstrated that the use of ultrasound was beneficial in patients who had both low and high pretest probability for needing incision and drainage. In patients suspected of having simple cellulitis (low pretest), ultrasound was used to change management in over half of participants; establishing the need for drainage due to imaging of a fluid collection. The opposite was true in the patients suspected of having an abscess (high pretest); the study found that ultrasound was able to determine that more than half of this group did not need drainage, because of the absence of a fluid collection on imaging.10 Other studies have had similar findings, but the percent change in management was slightly lower.11

A study by Barbic et al. demonstrated that POCUS provided a rapid, non-invasive, painless, and easily repeatable test, that distinguished between abscess and cellulitis in the vast majority of cases. Their analysis concluded that POCUS had a sensitivity of 96.2% and a specificity of 82.9% in diagnosing the presence of an abscess.12 They concluded that POCUS can accurately diagnose abscess in paediatric and adult populations and is likely superior to clinical examination.12


Cobblestones

Classic finding for cellulitis (but not specific to cellulitis). There will be hyperechoic lobules of subcutaneous fat surrounded by relatively hypoechoic inflammatory fluid.13

Cobblestone – Cellulitis

Purulent Fluid Collection

Classic finding for an abscess; have a rounded shape of anechoic or hypoechoic fluid collection, and there will be surrounding areas of cobblestones from the overlying cellulitis.13 As well, there should be no color flow if doppler is applied to the area (helping to distinguish from lymph node or vessel).14

Abscess – Anechoic Collection
Possible Abscess or Lymph Node? – This is a lymph node – see below
Colour flow differentiates lymph node from abscess

Necrotizing Fasciitis

Because you do not want to miss it! Findings via ‘STAFF’; subcutaneous thickening, air, and fascial fluid.14 Note, that ultrasound does not to exclude the diagnosis. Also need clinical correlation to increase suspicion of such a serious infection.15

Necrotizing Fasciitis – STAFF

Treatment:

According to The Infectious Diseases Society of America (2014) guidelines, management of SSTIs is differentiated based on the presence/absence of purulence (i.e. abscess/fluid collection). They recommend that all purulent infections be treated with incision and drainage, with more severe infections (signs of systemic involvement) being cultured with sensitivities in order to add antibiotics to the treatment.16 Otherwise, non-purulent infections are to be treated with systemic antibiotics; the severity of the infection determining the route and choice of agent.16

Antibiotic therapy, in addition to incision and drainage of a skin abscess, is suggested for patients with any of the following:17

  • Single abscess ≥2 cm or multiple abscesses
  • Large are of surrounding cellulitis
  • Patients with immunosuppression or other comorbidities
  • Signs of systemic involvement (fever > 38°C, hypotension, or tachycardia)
  • Poor clinical response to incision and drainage alone
  • Presence of an indwelling medical device
  • High risk for adverse outcomes with endocarditis (these include a history of infective endocarditis, presence of prosthetic valve or prosthetic perivalvular material, unrepaired congenital heart defect, or valvular dysfunction in a transplanted heart)
  • High risk for transmission of aureus to others (such as in athletes or military personnel)

 

Horizon Health’s local trends recommend the following (see guideline or Spectrum app for full details)

Severity of Infection

 

 

Antibiotic

Mild

Moderate

Severe

Cephalexin 500 – 1000mg PO q6h x 5 days

ceFAZolin 2 g IV q8h x 5 days

ceFAZolin 2 g IV q8h +/- Clindamycin 900 mg IV q8h

If true beta-lactam allergy

Cefuroxime 500 mg PO BID or TID x 5 days

Clindamycin 600-900 mg IV q8h x5 days

 

If MRSA suspected

Septra 800/160 mg or 1600/320 mg PO q12h x 5 days

Vancomycin 25-30 mg/kg IV once then 15mg/kg IV q8 to q12h x 5 days

ADD Vancomycin 25-30 mg/kg IV once then 15mg/kg IV q8 to q12h

 


Some research is suggesting that POCUS can take the assessment of abscesses one step-further and impact management based on the depth and size of the fluid collection seen in imaging. Russell et al. found that abscesses less than 0.4cm below the skin surface could be effectively treated without incision and drainage.18 Another study found that patients, with skin abscesses less than or equal to 5cm in diameter, treatment with oral antibiotics in combination with incision and drainage had improved short-term outcomes compared to those patients treated with the procedure alone.18 While as mentioned above, UpToDate, suggests that antibiotics be used in single abscess greater than 2 cm in size. As well, research has found that ultrasound guided incision and drainage provides lower failure rates (less recurrent infections or multiple incisions) compared to blind incision and drainage. Likely due to better visualization of the abscess and more adequate initial drainage.19


Limitations

There are some limitations to POCUS for SSTIs: ultrasound imaging and interpretation rely on the user’s ability to obtain high-quality images in order to assess whether an abscess is present. It is important for the user to be familiar with different findings on ultrasound to guide appropriate treatment. An abscess may appear hypoechoic, hyperechoic, or anechoic (depending on tissue contents), and usually has posterior acoustic enhancement.19 Determining if it is drainable can be difficult due to this variability in imaging, and it is also quite common for early abscesses to present like cellulitis with erythema, no fluctuance, and an ultrasound that is negative for a fluid collection.20 In cases of a suspected evolving abscess, sometimes referred to as a non-ripe abscess, supportive care, including warm compresses, pain control, and close follow-up, is recommended.20 The practitioner may treat this like cellulitis; however, the patient may return with perceived failure of therapy if discharge advice does not include the possibility of of an abscess forming over time.


Abscess examples from the SJ archives


References

  1. Moffarah AS, Al Mohajer M, Hurwitz BL, Armstrong DG. Skin and Soft Tissue Infections. Microbiol Spectr. 2016 Aug;4(4). doi: 10.1128/microbiolspec.DMIH2-0014-2015.

 

  1. Martinez, N. “Skin and Soft-Tissue Infections: Itʼs More Than Just Skin Deep.” Advanced Emergency Nursing Journal, vol. 42, no. 3, 2020, pp. 196–203.

 

  1. Cieri, B., Conway, E., Sellick, J., & Mergenhagen, K. (2019). Identification of risk factors for failure in patients with skin and soft tissue infections. The American Journal of Emergency Medicine, 37(1), 48-52.

 

  1. Borgundvaag, B., Ng, W., Rowe, B., Katz, K., Farrell, Brian, Guimont, Chantal, . . . Gregson, Dan. (2013). Prevalence of methicillin-resistant Staphylococcus aureus in skin and soft tissue infections in patients presenting to Canadian emergency departments. CJEM, 15(3), 141-160.

 

  1. Esposito, S., De Simone, G., Pan, A., Brambilla, P., Gattuso, G., Mastroianni, C., . . . Savalli, F. (2019). Epidemiology and Microbiology of Skin and Soft Tissue Infections: Preliminary Results of a National Registry. Journal of Chemotherapy (Florence), 31(1), 9-14.

 

  1. Stenstrom, R., Grafstein, E., Romney, M., Fahimi, J., Harris, D., Hunte, G., . . . Christenson, J. (2009). Prevalence of and risk factors for methicillin-resistant Staphylococcus aureus skin and soft tissue infection in a Canadian emergency department. CJEM, 11(5), 430-8.

 

  1. Spelman, D., Baddour, LM. (2020). Cellulitis and skin abscess: Epidemiology, microbiology, clinical manifestations, and diagnosis In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. Retrieved November 11, 2020. From: https://www.uptodate.com/contents/cellulitis-and-skin-abscess-epidemiology-microbiology-clinical-manifestations-and-diagnosis?search=abscess%20treatment&topicRef=110530&source=see_link#H2443336514

 

  1. Comer, Amanda B. “Point-of-Care Ultrasound for Skin and Soft Tissue Infections.” Advanced Emergency Nursing Journal, vol. 40, no. 4, 2018, pp. 296–303.

 

  1. Gaspari, R., Sanseverino, A., & Gleeson, T. (2019). Abscess Incision and Drainage With or Without Ultrasonography: A Randomized Controlled Trial. Annals of Emergency Medicine, 73(1), 1-7.

 

  1. Tayal, V., Hasan, N., Norton, H., & Tomaszewski, C. (2006). The Effect of Soft‐tissue Ultrasound on the Management of Cellulitis in the Emergency Department. Academic Emergency Medicine, 13(4), 384-388.

 

  1. Alsaawi, A., Alrajhi, K., Alshehri, A., Ababtain, A., & Alsolamy, S. (2017). Ultrasonography for the diagnosis of patients with clinically suspected skin and soft tissue infections: A systematic review of the literature. European Journal of Emergency Medicine, 24(3), 162-169.

 

  1. Barbic, D., Chenkin, J., Cho, D., Jelic, T., & Scheuermeyer, F. (2017). In patients presenting to the emergency department with skin and soft tissue infections what is the diagnostic accuracy of point-of-care ultrasonography for the diagnosis of abscess compared to the current standard of care? A systematic review and meta-analysis. BMJ Open, 7(1), E013688.

 

  1. Atkinson DP, Bowra J, Harris T, Jarman B, Lewis D, editors. Point of Care Ultrasound for Emergency Medicine and Resuscitation. Oxford University Press; 2019. pp. 140, 199-200.

 

  1. Gottlieb, M., Schmitz, G., Grock, A., & Mason, J. (2018). What to Do After You Cut: Recommendations for Abscess Management in the Emergency Setting. Annals of Emergency Medicine, 71(1), 31-33.

 

  1. Castleberg, E., Jenson, N., & Dinh, V. (2014). Diagnosis of necrotizing faciitis with bedside ultrasound: The STAFF Exam. The Western Journal of Emergency Medicine, 15(1), 111-113.

 

  1. Stevens, D., Bisno, A., Chambers, H., Dellinger, E., Goldstein, E., Gorbach, S., . . . Wade, J. (2014). Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the infectious diseases society of America. Clinical Infectious Diseases : An Official Publication of the Infectious Diseases Society of America, 59(2), 147-159.

 

  1. Spelman, D., Baddour, LM. (2020). Cellulitis and skin abscess in adults: treatment. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. Retrieved November 11, 2020. From: https://www.uptodate.com/contents/cellulitis-and-skin-abscess-in-adults-treatment?search=abscess%20treatment&topicRef=110529&source=see_link

 

  1. Russell, F., Rutz, M., Rood, L., Mcgee, J., & Sarmiento, E. (2020). Abscess Size and Depth on Ultrasound and Association with Treatment Failure without Drainage. The Western Journal of Emergency Medicine, 21(2), 336-342.

 

  1. Gaspari, R., Sanseverino, A., & Gleeson, T. (2019). Abscess Incision and Drainage With or Without Ultrasonography: A Randomized Controlled Trial. Annals of Emergency Medicine, 73(1), 1-7.

 

  1. Thornton J, Hellmich T. Evaluation and Management of Abscesses in the Emergency Department. Emergency Medicine Reports. 2017 May 1;38(10).
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