What does a positive Prehn sign indicate and how is it treated?

Prehn Sign in Testicular Conditions

A negative Prehn sign indicates testicular torsion and requires immediate urological consultation for surgical exploration, as testicular viability may be compromised if not treated within 6-8 hours of symptom onset. 1, 2

Understanding Prehn Sign

Prehn sign refers to the relief of testicular pain when the scrotum is elevated. The interpretation of this physical examination finding is critical in differentiating between various causes of acute scrotal pain:

• A positive Prehn sign (pain relief with elevation) suggests epididymitis 1, 3
• A negative Prehn sign (no pain relief with elevation) is associated with testicular torsion 1, 4

Diagnostic Significance

The diagnostic value of Prehn sign must be understood in context:

• Prehn sign negativity in testicular torsion ranges from 0% to 89.5% in various studies 4
• While a negative Prehn sign increases the likelihood of testicular torsion, it is insufficiently sensitive to rule out torsion on its own 4
• Must be evaluated alongside other clinical findings including sudden onset of pain, severe pain, and absence of urethritis or urinary tract infection symptoms 1

Clinical Approach to Acute Scrotal Pain

When evaluating a patient with acute scrotal pain and a negative Prehn sign:

• Consider testicular torsion as the primary diagnosis until proven otherwise 1, 2
• Look for associated findings of testicular torsion:
  • High-riding testicle 2
  • Absent cremasteric reflex 2
  • Sudden onset of severe unilateral scrotal pain 1, 2
  • Nausea and vomiting 2

Treatment Approach

Based on the Prehn sign finding and clinical suspicion:

• For negative Prehn sign suggesting testicular torsion:

  • Immediate urological consultation 1
  • Prompt surgical exploration without delay for imaging if clinical suspicion is high 1, 2
  • Critical time window of 6-8 hours before permanent ischemic damage occurs 1, 2

• For positive Prehn sign suggesting epididymitis:

  • Appropriate antimicrobial therapy based on likely pathogens 3
  • For younger men (14-35 years): target Chlamydia trachomatis and Neisseria gonorrhoeae with ceftriaxone and doxycycline 3
  • For older men: target coliform bacteria with fluoroquinolones like ofloxacin or levofloxacin 3

Important Caveats

• Prehn sign alone is not definitive - one study found that 33% of patients with confirmed testicular torsion had a positive Prehn sign 4
• If history and physical examination suggest torsion, immediate surgical exploration is indicated and should not be postponed for imaging studies 2
• Delay in treatment may result in decreased fertility or necessitate orchiectomy 2
• Doppler ultrasound can be helpful when diagnosis is uncertain, looking for decreased/absent blood flow and the "whirlpool sign" 1

Other Differential Diagnoses

When evaluating acute scrotal pain with Prehn sign:

• Consider torsion of the appendix testis, which may present similarly but has a positive blue dot sign on examination 5
• Rare causes include tumors, segmental testicular infarction, testicular vasculitis, and referred pain from conditions like pancreatitis 6

Remember that testicular torsion is a surgical emergency, and the negative predictive value of Prehn sign is not high enough to exclude torsion. When in doubt, urgent urological consultation is warranted.