Undescended testicle occurs when one or both testicles fail to move into the scrotum before birth.

Undescended 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 sometimes not.

This occurs because of the strength of the muscle reflex (cremasteric reflex) that retracts the testicles and the small size of the testicles before puberty. In this instance, the testicles descend at puberty. This is considered a type of normal. Surgical correction is not needed.

Testicles that do not descend by the time the child is 1 year old should be carefully evaluated. Studies suggest that surgery should be done by this age to confirm the diagnosis and to reduce the chances of permanent damage to the testicles.

Testicles that do not naturally descend into the scrotum are considered abnormal. These undescended testicles have an increased likelihood of developing cancer, regardless of whether or not they are brought down into the scrotum.

Bringing the testicle into the scrotum maximizes sperm production and increases the odds of good fertility. It also allows examination for early detection of testicular cancer.

In other cases, such as vanished testis, no testicle may be found, even during a surgical procedure. This may be due to a problem that occurs while the baby was still developing in the mother. It may be present at birth (congenital).

There are usually no symptoms, except that the testicle cannot be found in the scrotum (this may be described as an empty scrotum). Adult males with an undescended testicle may have problems with infertility.

An examination confirms that one or both of the testicles are not in the scrotum.

The health care provider may or may not be able to feel the undescended testicle in the abdominal wall above the scrotum.

Usually the testicle will descend into the scrotum without any intervention during the first year of life. If this does not occur, the child may receive hormone injections (B-HCG or testosterone) to try to bring the testicle into the scrotum.

Surgery (orchiopexy) is the main treatment. Earlier surgery may prevent irreversible damage to the testicles. This damage can cause infertility.

Most cases get better on their own, without any treatment. Medical or surgical correction of the condition is usually successful.

About 5% of patients with undescended testicles do not have testicles that can be found at the time of surgery. This is called a vanished or absent testis.

If one or both testicles do not descend, a man may be infertile later in life. Men who have an undescended testicle at birth are at higher risk of developing testicular cancer in both testes.

Call your child's health care provider if he appears to have an undescended testicle.

Call your provider if you are a male, 15 years or older and you are unsure how to perform testicular self-examination (TSE) to screen for testicular cancer.

Schneck FX, Bellinger MF. Abnormalities of the testes and scrotum and their surgical management. In: Wein AJ, ed. Campbell-Walsh Urology. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 127.