An undescended testicle (cryptorchidism) is one that remains inside the body and has not moved down into the scrotum. Normally the testicles, which form inside the abdomen of an unborn baby boy, descend into the sac beneath the penis (scrotum) by the time the baby is born.

One or both testicles may be affected. In most cases, the testicle will descend without treatment by the time the baby is 3 months old. If this does not happen, a doctor may advise surgery—laparoscopy or orchiopexy—to move the testicle into the scrotum.

A male who has undescended testicles has an increased risk of testicular torsion, hernia formation, infertility, and testicular cancer.