Prehn Sign in Testicular Pain Evaluation
Direct Answer
Prehn sign is an unreliable clinical test that should NOT be used to differentiate testicular torsion from epididymitis, and any patient with acute testicular pain must be treated as a potential surgical emergency until torsion is excluded through imaging or surgical exploration. 1
Why Prehn Sign Is Unreliable
A negative Prehn sign (pain not relieved with testicular elevation) is mentioned as a distinguishing feature of testicular torsion, but this physical examination maneuver has significant overlap between conditions and cannot reliably rule in or rule out torsion. 1, 2
- The clinical presentations of testicular torsion and epididymitis overlap substantially, making physical examination findings alone insufficient for diagnosis 1
- Scrotal elevation techniques can be "helpful" in theory but are not definitive enough to guide management decisions 2
- The critical error is relying on any single physical examination finding when testicular viability is compromised if not treated within 6-8 hours of symptom onset 1
The Correct Diagnostic Approach
High Clinical Suspicion (Immediate Surgical Exploration)
When testicular torsion is strongly suspected based on clinical presentation, proceed directly to surgical exploration without any diagnostic imaging studies. 1, 3
- Abrupt onset of severe scrotal pain is the hallmark of torsion 1
- Nausea and vomiting are common associated symptoms 1, 4
- The TWIST score can assist with risk stratification but should not be used in isolation 4
Intermediate Clinical Suspicion (Urgent Doppler Ultrasound)
For intermediate suspicion cases (TWIST score 1-5), obtain urgent Duplex Doppler ultrasound within 1-2 hours, but do not delay surgical exploration if imaging cannot be obtained rapidly. 1, 3
- Doppler ultrasound has sensitivity of 69-96.8% and specificity of 87-100% for testicular torsion 1
- Critical pitfall: False-negative Doppler evaluations occur in 30% or more of cases, particularly with partial torsion or early presentation 1
- Key ultrasound findings for torsion include decreased/absent blood flow, "whirlpool sign" of twisted spermatic cord, and enlarged heterogeneous testis 1
- Key ultrasound findings for epididymitis include enlarged epididymis with increased blood flow on color Doppler 1
Low Clinical Suspicion
Even with low clinical suspicion and normal imaging, any patient requires daily follow-up until symptoms completely resolve, as intermittent torsion can occur. 3
Critical Clinical Pitfalls to Avoid
- Never delay surgical consultation while waiting for imaging if clinical suspicion is high 1, 3
- A normal ultrasound examination cannot exclude the diagnosis of testicular torsion 4
- Presence of documented Doppler flow within the testis does not rule out torsion, as partial torsion can preserve some arterial flow 5
- Normal urinalysis does not exclude testicular torsion 1
- The cremasteric reflex is not a reliable indicator of disease presence or absence 4
Age-Specific Considerations
- Testicular torsion has a bimodal distribution with peaks in neonates and postpubertal boys (12-18 years), though it can occur in adults 1, 4
- Epididymitis is overwhelmingly the most common cause of testicular pain in adults over 25 years 1
- Torsion of testicular appendage is the most common cause in prepubertal boys 1
Management Algorithm
When testicular torsion is confirmed or highly suspected, immediate urological consultation and surgical exploration must occur within 6-8 hours of symptom onset to prevent permanent testicular loss. 1
- Surgical outcomes are significantly better when surgery occurs within this critical time window 1
- Manual detorsion can be attempted in the emergency department while awaiting transfer or consultation 4
- Bilateral orchiopexy should be performed during surgery to prevent contralateral torsion, as the bell-clapper deformity is present in 82% of patients with torsion 1