What are the clinical signs and diagnostic steps to identify testicular torsion in a patient presenting with acute scrotal pain?

Diagnosing Testicular Torsion

Testicular torsion is a clinical diagnosis that requires immediate urological consultation and surgical exploration when suspected—do not delay surgery to obtain imaging if clinical suspicion is high. 1

Clinical Presentation

The diagnosis begins with recognizing the characteristic presentation:

• Abrupt onset of severe, unilateral scrotal pain is the hallmark feature, distinguishing it from epididymitis which has gradual onset 1
• Nausea and vomiting commonly accompany the pain 2, 3
• Age matters significantly: bimodal distribution with peaks in neonates and postpubertal boys (12-18 years), though it can occur at any age 1, 4

Critical caveat: Testicular torsion can present without severe pain in rare cases, which can lead to dangerous delays in diagnosis—maintain a high index of suspicion even with atypical presentations 5

Physical Examination Findings

Key examination findings that strongly suggest torsion:

• Absent cremasteric reflex on the affected side is the most accurate physical examination sign 4
• High-riding testicle with abnormal lie 3
• Negative Prehn sign: pain is NOT relieved when elevating the testicle (unlike epididymitis) 1
• Red, swollen scrotum with acutely tender testicle 2

Risk Stratification

Use the TWIST score (Testicular Workup for Ischemia and Suspected Torsion) for systematic risk assessment in patients 3 months to 18 years 1:

• High clinical suspicion (TWIST score >5): Proceed directly to surgical exploration without imaging 1
• Intermediate suspicion (TWIST score 1-5): Obtain urgent Duplex Doppler ultrasound 1
• Low suspicion: Consider alternative diagnoses but remain vigilant

Diagnostic Imaging When Indicated

Duplex Doppler ultrasound is the first-line imaging modality when clinical suspicion is intermediate 1:

Ultrasound Protocol Components

• Grayscale examination to assess:

  • Testicular homogeneity and size 1
  • "Whirlpool sign" of twisted spermatic cord (96% sensitivity, most specific finding) 1, 6
  • Enlarged heterogeneous testis appearing hypoechoic 1
  • Ipsilateral hydrocele and scrotal wall thickening 1

• Color/Power Doppler assessment:

  • Decreased or absent blood flow to affected testicle compared to contralateral side (sensitivity 96-100%) 1
  • Power Doppler is particularly useful in prepubertal boys with normally slow flow 1
  • Always use the contralateral asymptomatic testicle as internal control 1

• Spectral Doppler analysis of upper, mid, and lower poles:

  • Diminished arterial velocity 1
  • Decreased or absent diastolic flow 1
  • Increased resistive index or reversed diastolic flow 1

Critical Imaging Limitations

Ultrasound sensitivity ranges from 69% to 96.8%, meaning false-negative evaluations occur in up to 30% of cases 1:

• Partial torsion (<450 degrees) may show preserved arterial flow because venous obstruction occurs first 1
• Early presentation within first few hours may appear normal 1
• Spontaneous detorsion can cause false-negative results 1
• Prepubertal boys normally have reduced intratesticular blood flow, potentially causing false-positives 1

When clinical suspicion remains high despite normal or equivocal ultrasound findings, proceed immediately to surgical exploration 1

Differential Diagnosis to Exclude

Compare clinical features systematically:

• Epididymitis/epididymo-orchitis: Gradual pain onset, enlarged epididymis with increased blood flow on Doppler, may have abnormal urinalysis (though normal urinalysis doesn't exclude either condition) 1
• Torsion of testicular appendage: Most common in prepubertal boys, "blue dot sign" (only visible in 21% of cases), normal testicular perfusion with localized hyperemia 1
• Segmental testicular infarction: Wedge-shaped avascular area on ultrasound, median age 37-38 years 1

Diagnostic Algorithm

1. Any acute scrotal pain = potential surgical emergency until torsion excluded 1
2. High clinical suspicion (sudden severe pain, absent cremasteric reflex, high-riding testis): Immediate urological consultation and surgical exploration—do not obtain imaging 1, 3
3. Intermediate suspicion: Urgent Duplex Doppler ultrasound with complete protocol 1
4. If ultrasound shows absent/decreased flow or whirlpool sign: Immediate surgical exploration 1
5. If ultrasound normal but clinical suspicion persists: Proceed to surgical exploration anyway 1

Time-Critical Nature

• 6-8 hour window from symptom onset before permanent ischemic damage occurs 1, 6
• Surgical outcomes significantly better when surgery occurs within 12 hours 1
• Testicular salvage rate of 90-100% if detorsion within 6 hours, dropping to <10% after 24 hours 3, 4

Common Pitfalls to Avoid

• Never delay surgical exploration for imaging when clinical suspicion is high 1, 3
• Do not be falsely reassured by normal urinalysis—it does not exclude torsion 1
• Do not dismiss cases with minimal pain—atypical presentations occur 5
• Do not rely solely on ultrasound—clinical judgment supersedes imaging when suspicion is high 1
• Remember that complete torsion (>450 degrees) shows absent flow, but partial torsion may show diminished flow, making diagnosis more challenging 1