As a baby boy grows inside his mother's womb, his testicles typically form inside his abdomen and move down (descend) into the scrotum shortly before birth. But in some cases, that move or descent doesn't occur, and the baby is born with a condition known as undescended testicles (or cryptorchidism).
Cryptorchidism is the most common genital abnormality in boys, affecting approximately 30% of baby boys born prematurely and about 4% born at term.
In about half of the babies, the undescended testicles move down or descend on their own by the sixth month of life. If descent doesn't happen by then, it's important to get treatment because testicles that remain undescended may be damaged, which could affect fertility later or lead to other medical problems.
Doctors usually diagnose cryptorchidism during a physical exam at birth or at a checkup shortly after. In 7 of 10 boys with an undescended testicle (or "testis"), it can be located or "palpated" on examination by the pediatric specialist.
In 3 of 10 boys, the testicle may not be in a location where it can be located or palpated, and may appear to be missing. In some of these cases, the testicle could be inside the abdomen. In some boys with a "non-palpable" testicle, however, the testicle may not be present because it was lost while the baby was inside the womb.
In some boys, the testicles (or "testes") may appear to be outside of the scrotum from time to time, which can raise the concern of an undescended testicle. Some of these boys may have the condition known as retractile testes. This is a normal condition in which the testes reside in the scrotum but on occasion temporarily retract or pull back up into the groin.
There is no need to treat a retractile testicle, since it is a normal condition, but it might require examination by a pediatric specialist to distinguish it from an undescended testicle.
If a baby's testicle has not descended on its own within the first 6 months of life, the boy should undergo evaluation by a pediatric specialist and treatment if the condition is confirmed. This usually involves surgically repositioning the testicle into the scrotum.
Treatment is necessary for several reasons:
The higher temperature of the body may inhibit the normal development of the testicle, which could impair normal production of sperm in the undescended testicle in the future, which could lead to infertility.
The undescended testicle is at a greater risk to form a tumor than the normally descended testicle.
The undescended testicle may be more vulnerable to injury or testicular torsion.
An asymmetrical or empty scrotum may cause a boy worry and embarrassment.
If surgery is done, it's likely to be an orchiopexy, in which a small cut is made in the groin and the testicle is brought down into the scrotum where it is fixed (or pexed) in place. Doctors typically do this on an outpatient basis, and most boys recover fully within a week.
Most doctors believe that boys who've had a single undescended testicle will have normal fertility potential and testicular function as adults, while those who've had two undescended testicles might be more likely to have diminished fertility as adults.
It is recommended that all boys who've had undescended testicles undergo follow-up evaluations by a urologist for years after their corrective surgeries.
It is important for all boys — even those whose testicles have properly descended — to learn how to do a testicular self-exam when they are teenagers so that they can detect any lumps or bumps that might be early signs of medical problems.