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A Case of Abdominal Pain in the Elderly – EM Reflections March 2022

Thanks to Dr. Paul Page for leading this month’s discussions

All cases are imaginary but highlight important learning points.

Authored and Copyedited by Dr. Mandy Peach

Case

An 82 yo male presents to the ED via EMS with 1 day of abdominal pain that started in the late evening. He describes feeling well all day, eating a healthy size dinner and then having sudden onset abdominal pain and distension just before bedtime. He can’t describe or localize the pain but states it is a ‘hard pain’ and has been associated with 2 episodes of nausea/vomiting. He doesn’t think he has had a fever. He is unsure of his last bowel movement and complains of frequent constipation. When asked about urinary changes he describes what sounds like a long-standing history of issues with urinary hesitance. He is unsure if there has been any acute change. He thinks there is no history of abdominal surgeries but “he’s been around a long time”. He is a lifelong non smoker.

PMH: DLP, HTN

Meds: Atorvastatin, Ramipril

Vitals: BP 110/60 HR 102 RR 18 O2 97% RA T – 36.5

On exam he appears in mild discomfort, with his eyes closed. His abdomen is mildly distended. He has generalized tenderness throughout the abdomen, no guarding or peritonitis. The testicles and inguinal region appear normal.

What are some barriers to assessing abdominal pain, or any presentation, in the geriatric patient?1,2

  • History may be difficult to intrepret, sometimes with vague symptoms
  • History may be difficult to obtain due to physical deficits like hearing loss
  • Vitals are not reliable – most patients are on beta blockers so their heart rate may not be elevated, and ‘normal’ blood pressure may actually be hypotensive for a geriatric patient who will often run much higher at baseline.
  • Blunted immune response – they may not illicit the typical fever or elevated WBC that we often count on to lead us to infectious/septic processes.
  • Decreased abdominal wall muscles lead to less guarding or rebound on exam – * peritoneal signs are often absent
  • Shrinkage of omentum leads to decreased containment of intraabdominal process
  • Higher rate of perforation and ischemic gut due to chronic issues like atheroscleoris and low flow states

He doesn’t look to be terribly unwell, you plan to treat his pain and nausea and order some labs.

What would be the drug of choice for abdominal pain in the elderly2?

Hydromorphone as it is not renally excreted.

You are ordering your labs – CBC, Cr, electrolytes, LFT’s, bilirubin, lipase and a urinanalysis.

Should you order a VBG and lactate in this man with ‘normal’ vitals and a non-specific abdominal exam2?

If the patient is presenting with pain out of proportion (ie. Ischemia symptoms) these tests are a must. But consider in any patient with risk factors for cardiovascular disease or atrial fibrillation. Our patient has a history of dyslipidemia and hypertension – you order the additional tests and ECG.

Elderly patients have vague abdominal pain all the time – what percentage are actually surgical?

Up to 60% of cases are surgical.

The associated mortality rate of those requiring abdominal surgery is upwards of 7x greater than younger patients with similar presentations.

What are the main causes of surgical abdominal pain the elderly1,2?

  • Cholecystitis – consider when working up a septic patient with no obvious source
  • Appendicitis
  • Bowel Obstruction – femoral hernia is a commonly missed cause
  • Hernia

Your patient had already been sent for an abdominal series after they were triaged. Certainly with the history of abdominal pain with n/v obstruction is high on the differential, even in a native abdomen.

What are useful findings on abdominal series3,4?

You are looking for the following:

  • Pneumoperitoneum (but really, you should be getting a CT if this is a concern)
  • Air fluid levels seen in obstruction

Certainly, in a busy department XR is quick, cheap and has minimal radiation. In patients with repeated SBO an XR may be suffice. Findings for SBO on XR include:

  • Dilated bowel with air fluid levels
  • Proximal bowel is dilated, but distal bowel is not
  • Gasless abdomen – where there is a large amount of fluid within the bowel loops, which may underestimate the level of obstruction. There may be a ‘string of pearls’ sign in upright films where small amount of air is seen between valvulae conniventes.

The sensitivity, specificity, and accuracy are 79-83%, 67-83%, and 64-82%, respectively3 – not enough to rely on when the mortality rate is so high in this population. A normal abdominal series does not rule out any serious pathology.

Certainly CT would be the gold standard – it would give the site, severity and etiology of obstruction. Complications such as necrosis, ischemia and perforation would be identified as well as other causes for abdominal pain on your differential. In elderly patients in particular, it has been shown to be more high yield for clinical decision making2.

But a CT takes time in an overcapacity and understaffed ED. While you wait for it to be completed you grab for your ultrasound probe – specifically you are looking for signs of SBO as that is top of your differential.

What is the accuracy of PoCUS for SBO5?

Sensitivity 88%, specificity 96%

What is an approach to a SBO scan with PoCUS?

Using your curvilinear probe ‘Mow the lawn’ starting in the RLQ and cover the entire abdomen using graded compression. Take your time6.

What are the findings5,7?

  • Dilated bowel loops >2.5cm
  • Thickened bowel wall >3mm
  • ‘To and fro’ peristalsis
  • Tanga sign – triangular shaped areas of free fluid between bowel loops. Concerning for high grade obstruction

You do confirm all signs of SBO, including tanga sign which is concerning.

By now your patient is over in the scanner when you get some lab results back – although the WBC is at the upper end of normal the lactate is significantly elevated.

While the patient is in CT waiting for a porter to come back you get a call from the radiologist confirming closed loop bowel obstruction with signs of ischemia and necrosis.

Bottom line – have a low threshold to order CT in geriatric abdominal pain. They are high risk patients, with high mortality rates.

 

References and further reading

  1. Thomas, A (2018). Approach to the Geriatric Patient. CRACKCast E181. CanadiEM. Retrieved July 19, 2022 from https://canadiem.org/crackcast-e181-approach-to-the-geriatric-patient/
  2. Melady, D, Lee, J, Helman, A. Geriatric Emergency Medicine. Emergency Medicine Cases. July, 2013. https://emergencymedicinecases.com/episode-34-geriatric-emergency-medicine/. Accessed July 19, 2022
  3. Bordeianou, L & Yeh, D. (2021) Etiologies, clinical manifestations, and diagnosis of mechanical small bowel obstruction in adults. Uptodate. Accessed July 2019 from https://www.uptodate.com/contents/etiologies-clinical-manifestations-and-diagnosis-of-mechanical-small-bowel-obstruction-in-adults?search=bowel%20obstruction%20adult&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1#H2918585369
  4. Jones, J., Ramsey, MD, A. Small bowel obstruction. Reference article, Radiopaedia.org. (accessed on 19 Jul 2022) https://doi.org/10.53347/rID-6158
  5. Atkinson P, Bowra J, Lewis D. (2019). Point of Care Ultrasound for Emergency Medicine and Resuscitation.
  6. Tooma, D & Dinh, V. Abdominal Ultrasound Made Easy: Step by Step Guide. Small Bowel Obstruction. POCUS 101. Accessed July 19, 2022 from https://www.pocus101.com/abdominal-ultrasound-made-easy-step-by-step-guide/#Small_Bowel_Obstruction_Ultrasound
  7. Small Bowel Obstruction. PoCUS Atlas. Accessed July 19, 2022 from https://www.thepocusatlas.com/gastrointestinal
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Small Bowel Obstruction & PoCUS

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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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