Rawan Alrashed (@rawalrashed)

PEM Physician

PoCUS Fellow

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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

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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).

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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):

 

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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)

 

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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).

 

 

 

 

 

 

 

 

 

 

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 :

 

 

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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)

 

 

 

 

 

 

 

 

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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).

 

 

 

 

 

 

 

 

 

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)

 

 

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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.

 

 

 

 

 

 

 

 

 

 

 

 

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).

 

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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)

 

 

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%.

 

 

 

 

 

 

 

 

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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%.

 

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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.