What is the appropriate evaluation and management of a pre‑pubertal boy with painless unilateral right scrotal swelling and increased vascularity on Doppler ultrasound?

Painless Unilateral Scrotal Swelling with Increased Vascularity

In a pre-pubertal boy presenting with painless unilateral right scrotal swelling and increased vascularity on Doppler ultrasound, epididymo-orchitis is the most likely diagnosis, but testicular torsion with reactive hyperemia from intermittent torsion-detorsion must be urgently excluded through careful clinical correlation and consideration of surgical exploration if any clinical suspicion remains. 1, 2

Critical Diagnostic Distinction

The combination of painless presentation and increased vascularity creates a diagnostic challenge that requires systematic evaluation:

Epididymo-Orchitis (Most Likely)

• Color Doppler demonstrates hyperemia with near 100% sensitivity for detecting scrotal inflammation, making increased blood flow the hallmark finding that distinguishes infection from torsion 1, 3
• Additional sonographic features include enlarged epididymis (hypoechoic or hyperechoic), scrotal wall thickening, and reactive hydrocele 1, 3
• Up to 20-40% of epididymitis cases progress to orchitis through direct retrograde spread, explaining testicular involvement 1
• In pre-pubertal boys, viral causes (especially mumps, Coxsackie, EBV) frequently present without pain and with normal inflammatory markers, relying on ultrasound hyperemia for diagnosis 3

Intermittent/Partial Testicular Torsion (Critical to Exclude)

• Reperfusion after early ischemia from torsion-detorsion episodes can induce reactive hyperemia on color Doppler that is sonographically indistinguishable from epididymo-orchitis 1, 2
• This represents a dangerous diagnostic pitfall where increased vascularity falsely reassures the clinician
• Partial torsion may present with less severe or even absent pain but still requires surgical intervention 2
• False-negative Doppler evaluations occur in up to 30% of cases, particularly with partial torsion or spontaneous detorsion 1, 2

Essential Clinical Correlation Points

Integration of clinical data is mandatory to distinguish these entities: 1

• Pain pattern: Waxing and waning pain suggests intermittent torsion; gradual onset favors infection 2
• Fever and systemic symptoms: Support infectious etiology, though viral orchitis often lacks fever 3
• Urinalysis: May be abnormal in bacterial epididymitis, but normal urinalysis does not exclude either diagnosis 2
• Age consideration: Pre-pubertal boys have normally reduced intratesticular blood flow, which can cause false-positive Doppler interpretations 1

Specific Ultrasound Features to Assess

Power Doppler is particularly valuable in pre-pubertal testes with slow flow states 2

Look for the "Whirlpool Sign"

• The twisted spermatic cord is the most specific ultrasound sign of torsion (96% sensitivity), appearing as a spiral twist with congested pseudomass below the torsion point 1, 2
• This finding can coexist with increased vascularity if reperfusion has occurred

Spectral Doppler Analysis

• Perform spectral Doppler in upper, mid, and lower poles of each testicle to detect regional flow variations 1, 2
• Worrisome waveforms include monophasic pattern, tardus-parvus morphology, decreased diastolic flow, or reversed diastolic flow 1
• Compare to the contralateral asymptomatic testicle as an internal control 1, 2

Grayscale Findings

• Enlarged heterogeneous testis (hypoechoic) suggests torsion 1
• Enlarged epididymis with preserved testicular homogeneity favors infection 1, 3

Management Algorithm

If Clinical Suspicion for Torsion Remains High:

Proceed immediately to urological consultation and surgical exploration within 6-8 hours, even with increased vascularity on Doppler 2, 4

• Testicular viability is compromised after 6-8 hours of ischemia 2
• The presence of hyperemia does not exclude intermittent torsion 1, 2

If Epididymo-Orchitis is Confirmed:

• Age-based pathogen evaluation: In pre-pubertal boys, consider viral etiologies (mumps serology, viral PCR) and atypical organisms 3
• Empiric treatment without awaiting inflammatory markers: Supportive care with bed rest, scrotal elevation, and analgesics 3, 4
• Antibiotics are typically not indicated for viral orchitis unless bacterial superinfection is suspected 3

Mandatory Re-evaluation:

• Clinical reassessment at 48-72 hours; lack of improvement mandates reconsideration of alternative diagnoses (testicular tumor, abscess, tuberculosis, fungal infection) and prompt surgical consultation 3

Critical Pitfalls to Avoid

• Never assume increased vascularity definitively excludes torsion—reperfusion hyperemia mimics infection 1, 2
• Do not delay surgical exploration based solely on Doppler findings when clinical suspicion is high—sensitivity ranges only 69-96.8% 1, 2
• Pre-pubertal boys normally have reduced testicular flow, making Doppler interpretation more challenging and prone to false-positives 1
• Painless presentation does not exclude torsion—partial or intermittent torsion may have minimal symptoms 2

Additional Differential Considerations

Testicular Tumor

• Small tumors (<1.5 cm) are hypovascular; larger tumors (>1.5 cm) are hypervascular 5
• Painless presentation with increased vascularity in a solid intratesticular mass warrants tumor marker evaluation (AFP, β-hCG, LDH) 6
• 17.9% of hypervascular solid testicular lesions prove benign on pathology, particularly smaller non-palpable lesions without elevated markers 6

Acute Idiopathic Scrotal Edema

• Rare, self-limiting condition in pre-pubertal boys 2, 4
• Marked scrotal wall thickening with heterogeneous striated appearance and increased peritesticular blood flow, but normal testicular vascularity 4
• Diagnosis of exclusion after ruling out surgical emergencies 2