Undescended testes, also known as cryptorchidism, is a common condition where one or both of a boy's testicles are not in the scrotum. During pregnancy, the testicles form inside a baby boy's abdomen and gradually move down into the scrotum before birth. Around 1 in 20 male babies is born with an undescended testicle. In most cases, treatment is not required as the testicle will often move down into the scrotum naturally during the first six months of life. In about 1 in 70 cases, however, the testicle remains undescended.
Most boys with undescended testes are otherwise completely healthy. It's unknown why some boys are born with undescended testicles. It is more common in premature births, low birth weight and those with a family history of undescended testicles.
Undescended testicles are usually diagnosed after a physical examination. It needs to be differentiated from retractile testes where the testes have descended into the scrotum normally, but retract into the groin when cold, such as during an examination. If the testicles are not easily felt, scans may be required to identify their position. Occasionally, part of the initial surgical treatment may involve keyhole surgery to see if the testicles are inside the abdomen.
If the testicles haven't descended within a year of birth, they're unlikely to do so. Treatment will usually be recommended as testicles do not seem to develop if left in the abdomen. Boys with undescended testicles can have fertility problems in later life and an increased risk of developing testicular cancer if untreated. Treatment involves an operation called an orchidopexy to move the testicles into the correct position inside the scrotum.