Undescended testes (cryptorchidism) are testes that remain in the abdomen instead of descending into the scrotum just before birth. Retractile testes have descended into the scrotum but can move back (retract) into the inguinal canal easily as a reflex response to stimulation.
About 3 of every 100 boys have undescended testes at birth. Most of these testes descend on their own within about 6 months. Boys born prematurely are much more likely to have the condition as are boys whose family members had undescended testes. About 10% are affected on both sides.
Undescended testes cause no symptoms. However, undescended testes can become twisted in the abdomen (testicular torsion—see see Testicular Torsion), impair sperm production later in life, and increase the risk of hernia and testicular cancer. Surgery is usually performed to bring the testes down into the scrotum if the testes remain undescended at 1 year of age.
Retractile (hypermobile) testes are descended testes that easily move back and forth between the scrotum and the abdomen. Retractile testes do not lead to cancer or other complications. The testes usually stop retracting by puberty and do not require surgery or other treatment.
Last full review/revision October 2012 by Elizabeth J. Palumbo, MD