DefinitionUndescended testicle occurs when one or both testicles fail to move into the scrotum before birth.Alternative NamesCryptorchidism; Empty scrotum - undescended testes; Scrotum - empty (undescended testes); Monorchism; Vanished testes - undescended; Retractile testesCauses, incidence, and risk factorsUndescended testicles are fairly common in premature infants. They occur in about 3 - 4% of full-term infants. In most cases the testicles descend by the time the child is 9 months old.Once a testicle has been discovered in the scrotum, it is generally considered descended even if it is temporarily pulled back (retracted) on a later examination.Sometimes a condition called retractile testes will develop. In this condition, the health care provider can sometimes locate the testicles and