Many baby boys have an undescended testicle at birth. This means that one of his testicles has not come down into the scrotum, the sack of skin under the penis that normally holds both testicles. This happens with about 3% of full-term baby boys and up to 30% of boys who are born prematurely. This condition is also called cryptorchidism. In some cases, both testicles are undescended.
However, an undescended testicle almost always moves down into the scrotum within a few months after birth. Even if it doesn’t, the condition can usually be corrected relatively easily.
Why Does This Happen?
Testicles are also called testes. Undescended testicles occur because the testicles do not form inside the scrotum during development. Instead, they form in the lower abdomen. During the development of a male fetus, the testicles travel down into the scrotum.
The reason testicles form in the abdomen early in development rather than in the scrotum is because the same two small bits of cells in the fetus can become either ovaries or testicles, depending on whether they receive hormonal signals from genes in the male chromosome. This formation into testicles or ovaries happens in the second trimester of pregnancy.
As the testicles form, they stay in the abdomen until the seventh month of pregnancy when they start to move through the abdomen down to a tube called the “inguinal canal” that connects the scrotum to the abdomen. The testicles then move into the scrotum just before birth, but may remain in the inguinal canal instead. In most cases of an undescended testicle, the testicle drops into its proper place in the scrotum within a few months after a boy’s birth.
Testicles need to descend into the scrotum because they cannot make sperm properly unless they are few degrees cooler than normal internal body temperature. The scrotum is 2 or 3 degrees cooler than the interior of the abdomen, and this allows sperm to form properly.
Some baby boys have what are called retractile testicles. This means that sometimes they are in their proper place in the scrotum and sometimes they have retracted up into the inguinal canal. An examination by your son’s pediatrician can determine if he has an undescended testicle or a retractile one.
In a very small number of cases, the testicle is not undescended, but is actually missing completely or is very small.
If your son’s testicle does not descend on its own, your baby boy may need to have a surgical procedure called orchiopexy. A pediatric surgeon moves the testicle into the scrotum and then uses a few stitches to make sure that it stays there. Your son will need general anesthesia for the surgery, but he can usually go home the same day and will need only a couple of days to recover completely. In cases where the testicle is all the way up in the abdomen, it may need to be removed completely. Your son will still have good fertility when he becomes an adult even with only one testicle.
In some baby boys, an undescended testicle may be accompanied by an inguinal hernia, where a loop of intestine has come through the inguinal canal and into the scrotum. An inguinal hernia can be fixed surgically at the same time the orchiopexy is done.
If your son has a testicle that does not descend, your pediatrician may refer him to a urologist or a pediatric urologist for examination and treatment.
Potential Complications of Cryptorchidism
It is very important that an undescended testicle be watched to ensure that it descends into the scrotum. An undescended testicle increases the risk of your son developing testicular cancer later in life. Aa testicle that remains lodged in the abdomen must be removed if it cannot be brought down into the scrotum.
The American Urological Association and the Urology Care Foundation have more information about undescended testicles here.