Prehn's sign (named after urologist Douglas T. Prehn) is a medical diagnostic indicator that was once believed to help determine whether the presenting

testicular pain Testicular pain, also known as scrotal pain, occurs when part or all of either one or both testicles hurt. Pain in the scrotum is also often included. Testicular pain may be of sudden onset or of long duration. Causes range from non serious musc ...

is caused by acute

epididymitis Epididymitis is a medical condition characterized by inflammation of the epididymis, a curved structure at the back of the testicle. Onset of pain is typically over a day or two. The pain may improve with raising the testicle. Other symptoms may ...

or from

testicular torsion Testicular torsion occurs when the spermatic cord (from which the testicle is suspended) twists, cutting off the blood supply to the testicle. The most common symptom in children is sudden, severe testicular pain. The testicle may be higher than u ...

. Although elevation of the scrotum when differentiating epididymitis from testicular torsion is of clinical value, Prehn's sign has been shown to be inferior to Doppler ultrasound to rule out testicular torsion. According to Prehn's sign, the physical lifting of the testicles relieves the pain of epididymitis but not pain caused by testicular torsion. * Negative Prehn's sign indicates no pain relief with lifting the affected testicle, which points towards testicular torsion which is a surgical emergency and must be relieved within 6 hours. *Positive Prehn's sign indicates there is pain relief with lifting the affected testicle, which points towards epididymitis. Another way to differentiate between epididymitis and torsion on physical examination is checking for the

cremaster reflex The cremasteric reflex is a superficial (i.e., close to the skin's surface) reflex observed in human males. This reflex is elicited by lightly stroking or poking the superior and medial (inner) part of the thigh—regardless of the direction of ...

which is classically absent in the case of torsion.

History

It was discovered in 1934, by Douglas T. Prehn (August 1, 1901 – June 30, 1974), a prominent American urologist in Wisconsin.

References

{{Eponymous medical signs for reproductive system Medical signs