Prehn's sign

{{Short description|Medical sign for testicular pain}}

Image:Illu testis surface.jpg)]]

Prehn's sign (named after urologist Douglas T. Prehn){{cite journal|journal=British Journal of Urology|date=March 1935|volume=7|issue=1|pages=56–76|doi=10.1111/j.1464-410X.1935.tb11273.x|title=Abstracts from Current Literature}} is a medical diagnostic indicator that was once believed to help determine whether the presenting testicular pain is caused by acute epididymitis or from testicular torsion.{{Cite web |url=http://www.aafp.org/afp/990215ap/817.html |title=Diagnosis and Treatment of the Acute Scrotum - February 15, 1999 - American Academy of Family Physicians |access-date=August 23, 2008 |archive-date=June 6, 2011 |archive-url=https://web.archive.org/web/20110606042106/http://www.aafp.org/afp/990215ap/817.html |url-status=dead }} 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.{{Cite journal|vauthors=Lavallee ME, Cash J |title=Testicular torsion: evaluation and management |journal=Curr Sports Med Rep |volume=4 |issue=2 |pages=102–4 |date=April 2005 |pmid=15763047 |doi= 10.1097/01.CSMR.0000306081.13064.a2|s2cid=209145837 |doi-access=free }}

According to Prehn's sign, the physical lifting of the testicles relieves the pain of epididymitis but not pain caused by testicular torsion.{{Cite web |url=http://www.hawaii.edu/medicine/pediatrics/pedtext/s13c10.html |title=Case Based Pediatrics Chapter |access-date=2008-10-18 |archive-date=2008-10-24 |archive-url=https://web.archive.org/web/20081024072418/http://www.hawaii.edu/medicine/pediatrics/pedtext/s13c10.html |url-status=live }}

• 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 which is classically absent in the case of torsion.