What is the best diagnostic method to confirm testicular torsion in a young male patient presenting with acute testicular pain?

Diagnostic Confirmation of Testicular Torsion

The answer is C - Doppler ultrasound is the established first-line imaging modality to confirm testicular torsion, though surgical exploration should never be delayed when clinical suspicion is high. 1

Why Doppler Ultrasound is the Correct Answer

Doppler ultrasound serves as the primary diagnostic tool with sensitivity ranging from 69-96.8% and specificity of 87-100%. 1 The American College of Radiology specifically recommends Duplex Doppler ultrasound as the first-line imaging study for suspected testicular torsion. 1, 2

Key Ultrasound Findings That Confirm Torsion

• Decreased or absent blood flow to the affected testicle compared to the contralateral side is the hallmark finding 1
• The "whirlpool sign" of the twisted spermatic cord on grayscale examination has 96% sensitivity 1, 2
• Enlarged heterogeneous testis that appears hypoechoic on grayscale imaging 1
• Color Doppler assessment of testicular perfusion demonstrates sensitivity of 96-100% 1, 2
• Power Doppler is particularly useful in prepubertal boys who normally have reduced intratesticular blood flow 1, 2

Why the Other Options Are Incorrect

• CT scan (Option A) is not mentioned in any guidelines as a diagnostic tool for testicular torsion and would expose the patient to unnecessary radiation and delay definitive treatment 1
• MRI (Option B) can identify the "bell-clapper" deformity with 83% sensitivity, but is impractical in the acute setting due to time constraints when the critical window is 6-8 hours 1
• X-ray (Option D) has no role in diagnosing testicular torsion as it cannot evaluate blood flow or soft tissue structures 1

Critical Clinical Pitfalls to Avoid

False-negative Doppler evaluations occur in up to 30% of cases, particularly with partial torsion or spontaneous detorsion. 1 This is the most dangerous pitfall because it can lead to delayed surgery and testicular loss. 3

When Ultrasound Can Mislead You

• Partial torsion (<450 degrees) may show preserved arterial flow because venous obstruction occurs first, while arterial flow persists 1
• Early presentation within the first few hours may show normal-appearing testis 1
• Subacute torsion (>8 hours) can show inhomogeneous testicle with alternating hypoechoic and hyperechoic areas that mimic tumor or epididymitis 3
• Prepubertal boys normally have reduced intratesticular blood flow, which can lead to false-positive interpretations 1, 2

The Critical Management Algorithm

When clinical suspicion for testicular torsion is high, immediate urological consultation and surgical exploration should proceed regardless of ultrasound findings. 1, 2 This is because testicular viability is compromised if not treated within 6-8 hours of symptom onset. 1

Proper Ultrasound Technique to Maximize Accuracy

• Grayscale examination to assess testicular homogeneity and identify the whirlpool sign 1, 2
• Color/Power Doppler assessment comparing blood flow to the contralateral testis 1, 2
• Spectral Doppler analysis of upper, mid, and lower poles of each testicle to detect regional flow variations 1
• Use the contralateral asymptomatic testicle as an internal control for comparison 1

When to Bypass Imaging Entirely

If clinical suspicion is high based on abrupt onset of severe scrotal pain, absent cremasteric reflex, and negative Prehn sign, proceed directly to surgical exploration without waiting for imaging. 1, 4 The sensitivity of CDUS performed by doctors on duty in real-world settings can be as low as 69.2%, meaning nearly one-third of torsions may be missed. 5

Time-Critical Nature of This Diagnosis

Surgical exploration and detorsion must occur within 6-8 hours of symptom onset to prevent permanent ischemic damage. 1, 2 Surgical outcomes are significantly better when intervention occurs within 12 hours maximum. 1, 2 Every minute of delay increases the risk of testicular loss. 4, 6