An undescended testicle has not moved into the scrotum, the bag of skin that hangs behind the penis, during the development of a fetus.
The American Urological Association report that 3–4 percent of full-term male newborns and 21 percent of those born prematurely have an undescended testicle. Usually, only one testicle does not descend. Both are undescended in 10 percent of cases.
The more formal medical term for testicles that do not descend is cryptorchidism. It is one of the most common endocrine problems in newborn males and the most common genital condition that doctors can identify at birth.
Cryptorchidism often corrects itself within a few months of birth. However, an infant sometimes needs surgery to relocate the testicle to the scrotum.
This article explores the causes of cryptorchidism, risk factors, and treatment methods.
What is cryptorchidism?
The testicles should descend into the scrotum while the fetus is developing.
Cryptorchidism occurs when one or both of the testicles do not descend into the scrotum while the fetus is developing.
During gestation, the testicles form in the abdomen and gradually drop through the inguinal canal into the scrotum at around month 8 of pregnancy.
The scrotum is a small pouch, or sac, of skin that hangs behind the penis.
The testicles are oval-shaped organs that form part of the male reproductive system.
The testicles produce sperm cells, which are vital to reproduction. They also make testosterone, a hormone that plays a key role in male sexual development.
Undescended testicles may be palpable or unpalpable.
Palpable means that a doctor will be able to feel the undescended testicle during a physical examination. About 80 percent of undescended testicles are palpable.
The testicle is usually located at the end of the inguinal canal, a channel that carries the spermatic cord towards the penis and scrotum.
If a doctor cannot feel the undescended testicle, it is unpalpable, and it may be:
Abdominal: The least common location for an undescended testicle is in the abdomen.
Inguinal: The testicle has moved into the inguinal canal, but not far enough to be detectable by touch.
Atrophic or absent: The testicle is either very small, or it has never formed.
A premature birth increases the risk of cryptorchidism.
The following factors may increase the risk of cryptorchidism:
premature birth, with an earlier delivery carrying a greater risk
a low birth weight, which may double or triple the risk
Down’s syndrome and other conditions that slow fetal growth
a family history of issues with genital development
tobacco consumption by a mother during pregnancy
In the early stages, all fetuses have structures that can develop into male or female reproductive organs.
The child receives sex chromosomes from its mother and father. Sex chromosomes are a pair of DNA molecules. The chromosomes will be XX in a female fetus, and XY if the fetus is male.
As the fetus develops, the XY gene promotes the development of the testes. These produce hormones that encourage the growth of the male reproductive tract, preventing female development.
Scientists maintain that the testicles might begin to develop incorrectly.
Abnormal genital development may also stem from androgen insensitivity syndrome (AIS), a genetic disorder in which XY fetuses do not respond to male hormones, such as testosterone.
A newborn with AIS may have female attributes, such as a short, pouch vagina, but no uterus, ovaries, or fallopian tubes. The testes may be present in the abdomen or the inguinal canal.