In a 30-year-old man with acute testicular pain, no history of trauma and no visible asymmetry, what diagnostic tests are indicated?

Diagnostic Testing for Acute Testicular Pain in a 30-Year-Old Male

Obtain urgent color Doppler ultrasound of the scrotum immediately, as this is the first-line imaging study that can differentiate between surgical emergencies like testicular torsion and medical conditions like epididymitis. 1

Immediate Diagnostic Approach

Primary Test: Color Doppler Ultrasound

Duplex Doppler ultrasound is the established first-line imaging modality with sensitivity of 69-96.8% and specificity of 87-100% for testicular torsion. 1 The examination must include three critical components:

• Grayscale examination to assess testicular homogeneity, identify the "whirlpool sign" (twisted spermatic cord with 96% sensitivity), and evaluate for scrotal wall thickening or hydrocele 2, 1

• Color/Power Doppler assessment comparing testicular perfusion to the contralateral side, with Power Doppler being particularly valuable for detecting low-flow states 2, 1

• Spectral Doppler analysis of the upper, mid, and lower poles of each testis to detect regional flow abnormalities, looking for monophasic patterns, tardus-parvus morphology, or reversed diastolic flow 2, 1

Ancillary Laboratory Testing

• Urinalysis should be obtained, though a normal result does not exclude either epididymo-orchitis or torsion 2

• Inflammatory markers may support infection if elevated, but viral orchitis often presents without fever or elevated markers 2

Critical Interpretation Pitfalls

Understanding Doppler Limitations

Up to 30% of torsion cases yield false-negative Doppler results, especially with partial torsion or spontaneous detorsion. 2 This is the most dangerous pitfall:

• Increased vascularity does not rule out torsion—reperfusion hyperemia after spontaneous detorsion can mimic epididymitis 2, 1

• Partial torsion may show diminished but present arterial flow because venous obstruction occurs first, creating diagnostic confusion 1

• Complete torsion >450 degrees shows straightforward absent arterial and venous flow, making diagnosis easier 1

Differential Diagnosis by Ultrasound Findings

If Doppler Shows Decreased/Absent Flow:

• Testicular torsion is the primary diagnosis—this is a surgical emergency requiring intervention within 6-8 hours 1
• Additional findings: enlarged heterogeneous hypoechoic testis, whirlpool sign, ipsilateral hydrocele 1

If Doppler Shows Increased Flow (Hyperemia):

• Epididymo-orchitis is most likely in adults—color Doppler hyperemia has near-100% sensitivity for detecting scrotal inflammation 2
• Additional findings: enlarged epididymis, scrotal wall thickening, reactive hydrocele 2
• However, do not assume increased vascularity rules out torsion—reperfusion can mimic infection 2

If Doppler Shows Normal Flow:

• Consider torsion of testicular appendage, early/intermittent torsion, or segmental testicular infarction 1
• If clinical suspicion for torsion remains high, proceed to immediate urological consultation and surgical exploration regardless of normal Doppler findings 1

Management Algorithm Based on Findings

High Clinical Suspicion for Torsion (Sudden Severe Pain):

Obtain immediate urological consultation and proceed to surgical exploration within 6-8 hours, regardless of Doppler findings. 1 Testicular viability declines sharply after this window, and Doppler sensitivity is imperfect at 69-96.8%. 1

Confirmed Epididymo-orchitis:

• Initiate supportive care: scrotal elevation, bed rest, analgesics 2
• Consider age-appropriate antibiotics if bacterial etiology suspected 2
• Re-evaluate at 48-72 hours; lack of improvement mandates reconsideration of alternative diagnoses 2

Key Clinical Distinguishing Features

• Abrupt onset of severe pain favors torsion, while gradual onset favors epididymitis 1
• Waxing-and-waning pain suggests intermittent torsion 2
• Negative Prehn sign (pain not relieved by testicular elevation) is a key feature of torsion 1
• Normal urinalysis does not exclude testicular torsion 1

Critical Time-Sensitive Principle

Do not delay surgical exploration based solely on Doppler findings when torsion suspicion is high. 2 The 6-8 hour window for testicular salvage is absolute, and false-negative Doppler evaluations occur in up to 30% of cases. 2, 1 In a 30-year-old male, while epididymitis is statistically more common, testicular torsion remains possible and must be urgently excluded given the catastrophic consequences of missed diagnosis.