Can Epididymitis Be Detected on Testicular Ultrasound?
Yes, epididymitis is readily detected on testicular ultrasound, which is the imaging modality of choice for evaluating acute scrotal conditions. 1
Ultrasound Findings in Epididymitis
Grayscale Features
- The epididymis appears enlarged and can show either increased or decreased echogenicity compared to normal tissue 1
- Scrotal wall thickening is commonly present 1
- A reactive hydrocele (fluid collection around the testis) frequently accompanies epididymitis 1, 2
Doppler Findings
- Increased blood flow (hyperemia) on color Doppler is the hallmark finding, with sensitivity approaching 100% for detecting scrotal inflammation 1, 3
- Power Doppler can be used as an adjunct to color Doppler and is particularly sensitive for detecting slow flow states 1
- The increased vascularity helps distinguish epididymitis from testicular torsion, which shows decreased or absent flow 1, 3
Extension to Orchitis
- Up to 20% of patients with epididymitis develop concomitant orchitis (epididymo-orchitis) 1
- When orchitis is present, the testis itself shows increased blood flow on Doppler imaging 1
- The combination of epididymal and testicular hyperemia confirms the diagnosis of epididymo-orchitis 4
Critical Diagnostic Considerations
Why Ultrasound Is Essential
- Ultrasound is crucial for differentiating epididymitis from testicular torsion, a surgical emergency that requires intervention within 6-8 hours 1, 3
- Testicular torsion shows decreased or absent blood flow, the opposite of epididymitis 1, 3
- Clinical examination alone can be unreliable for distinguishing these conditions, making Doppler ultrasound a critical diagnostic tool 5
Rare but Important Complications
- Global testicular infarction can rarely complicate severe epididymitis when funiculitis (inflammation of the spermatic cord) impedes testicular blood flow 6, 7
- In these cases, the testis may paradoxically show absent or reversed diastolic flow despite the inflammatory etiology 3
- This "string-of-beads" appearance of juxtaepididymal color Doppler signal has been associated with acute epididymo-orchitis complicated by testicular infarction 1
- Contrast-enhanced ultrasound can definitively establish global infarction when conventional Doppler is equivocal 7
Clinical Pitfall to Avoid
Do not assume epididymitis based on clinical presentation alone without imaging confirmation. Several cases have been reported where initial treatment with antibiotics for presumed epididymitis delayed the diagnosis of testicular torsion, resulting in testicular loss requiring orchidectomy 5. When Doppler ultrasound shows diminished or absent intratesticular flow in a patient with acute scrotal pain, immediate surgical exploration is warranted regardless of the clinical suspicion for epididymitis 5.