Prehn's sign

A clinical sign used to differentiate testicular torsion from epididymitis

Anatomy of the testis, showing the epididymis and surrounding structures.

Prehn's sign is a clinical diagnostic tool used in the evaluation of acute scrotal pain. It is primarily employed to differentiate between testicular torsion and epididymitis, two conditions that can present with similar symptoms but require different management strategies.

Clinical presentation

Patients presenting with acute scrotal pain may exhibit swelling, redness, and tenderness of the affected testis. The differential diagnosis for these symptoms includes testicular torsion, epididymitis, and other less common conditions such as orchitis or testicular cancer.

Procedure

To perform Prehn's sign, the examiner gently elevates the affected testis. The response to this maneuver helps in differentiating the underlying cause of the pain:

• In cases of epididymitis, the elevation of the testis typically relieves pain, resulting in a positive Prehn's sign.
• In contrast, testicular torsion usually does not result in pain relief upon elevation, indicating a negative Prehn's sign.

Pathophysiology

The rationale behind Prehn's sign lies in the anatomical and physiological differences between epididymitis and testicular torsion. Epididymitis is an inflammatory condition of the epididymis, often caused by infection, which can lead to increased blood flow and swelling. Elevation of the testis may reduce venous congestion and alleviate pain.

Testicular torsion, on the other hand, involves the twisting of the spermatic cord, leading to compromised blood supply to the testis. This condition is a surgical emergency, and the lack of pain relief upon elevation is due to the persistent ischemia.

Limitations

While Prehn's sign can be a useful clinical tool, it is not definitive. False positives and negatives can occur, and the sign should be interpreted in conjunction with other clinical findings and diagnostic tests, such as Doppler ultrasound of the scrotum.

Related pages

• Testicular torsion
• Epididymitis
• Orchitis
• Testicular cancer