The testicles develop before birth in the abdominal cavity. Normally, they descend into the scrotum before birth. Undescended testicle occurs when one or both testicles fail to move into the scrotum prior to birth.

Undescended testicles are fairly common in premature infants, and occur in about 3 to 4% of full-term infants. About 65% of the testicles typically descend by 9 months of age.

Once a testicle has been discovered in the scrotum, it is generally considered descended, even if it is temporarily retracted on a later examination. Sometimes a condition (referred to as retractile testes) will develop, in which the examiner can sometimes locate the testicles and sometimes not.

This occurs because of the strength of the muscular reflex (cremasteric reflex) that retracts the testicles and the small mass of the testicles before puberty. In this instance, the testicles descend at puberty. These testicles are considered a variant of normal and do not need surgical correction.

Testicles that do not descend by one year of age should be carefully evaluated. The literature suggest that definitive surgery should be accomplished by three years of age to confirm diagnosis and to lessen the likelihood of permanent testicular damage.

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

Bringing the testicle into the scrotum maximizes sperm production and thus 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 upon surgical exploration. This may be due to in utero vascular insult (testicular torsion), resulting in an infarction (death of affected tissue).

Alternatively, this may be associated with congenital anomaly, in which case blind ending blood vessels are seen in the vas deferens (the tube which normally carries sperm).

There are usually no symptoms other than inability to find the testicle within the scrotum (may be described as an empty scrotum). Adult males with an undescended testicle may complain of infertility.

Examination confirms that one or both of the testicles are not present in the scrotum.

The undescended testicle may or may not be able to be felt 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, hormonal injections (B-HCG or testosterone) may be given in an attempt to stimulate movement of the testicle into the scrotum.

Surgery (orchiopexy) is the definitive therapy. Recent literature suggest a trend favoring earlier surgery to prevent irreversible damage to the testis, which causes infertility.

The majority of cases resolve spontaneously, 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 testicle(s) does not descend, a man may be infertile later in life. Men who had an undescended testicle at birth are at higher risk of developing testicular cancer in that testicle (even after it has descended either spontaneously, with hormonal therapy, or through surgery).

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

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