What is an undescended testicle?

As a baby boy grows inside his mother, he develops testicles. Early in his development, his testicles are in his belly. Normally before he is born, his testicles move down into his scrotum, the sac that hangs below the penis. When one testicle does not move into the scrotum as it should, the baby has an undescended testicle. In rare cases, both testicles are undescended.

About 5 out of 100 baby boys are born with an undescended testicle.¹ It is most common in babies who were born before their due date or who were very small at birth. Why a baby’s testicle does not move into the scrotum is not well understood. It probably has a number of causes. This condition runs in some families (can be inherited).

In more than half of cases, the testicle descends on its own by the time the baby is 3 months old. If your baby’s testicle has not descended by the time he is 6 months of age, your doctor may suggest treatment.

What are the symptoms?

Having an undescended testicle does not cause pain or other symptoms. The scrotum may look a little smoother or less developed on one side, or the side without a testicle may look smaller and flatter.

How is an undescended testicle diagnosed?

At newborn and well-baby visits, your doctor will check your baby’s scrotum.

• If the testicle can be felt but it is not in the scrotum, the doctor will probably want to check your baby again at 3 to 6 months of age. By this time, the testicle may have moved into place on its own.
• Sometimes the doctor can't feel the testicle at all. It could still be in the baby's belly, it could be too small to feel, or it could be absent. After taking a wait-and-see approach, a doctor may recommend a type of surgery called laparoscopy to see if he or she can find the testicle. Laparoscopy requires only a small cut below the belly button, which heals quickly. During laparoscopy, the surgeon puts a tiny lighted instrument into the baby’s belly. The doctor may be able to move the testicle into the scrotum during this procedure so that the baby will most likely not need another surgery.
• If both testicles are undescended and cannot be felt in the groin, the doctor will do a blood hormone test to find out if the testicles are absent. It is rare to have two absent testicles.

Doctors sometimes use an imaging test, such as ultrasound, to help find an undescended testicle. These tests are more useful for older boys and men than for babies.

Some other conditions are closely related to undescended testicles. Your doctor will take care to make the correct diagnosis so your child can get the right treatment.

How is it treated?