undescended testicles

Cryptorchidism is a medical term referring to absence from the scrotum of one or both testes. This usually represents failure of the testis to move, or "descend," during fetal development from an abdominal position, through the inguinal canal, into the ipsilateral scrotum. About 3% of full-term and 30% of premature infant boys are born with at least one undescended testis, making cryptorchidism the most common birth defect of male genitalia. However, most testes descend by the first year of life (the majority within three months), making the true incidence of cryptorchidism around 1% overall.
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Cryptorchidism /crypt·or·chid·ism/ failure of one or both testes to descend into the scrotum.cryptor´chid Cryptorchidism Occurs when a boy is born [more]Undescended testicles - Community and Resources

A condition in which one or both testicles fail to move from the abdomen, where they develop before birth, into the scrotum. Undescended testicles may increase the risk for development of testicular cancer. Also called cryptorchidism.