During normal fetal development, according to Children’s Hospital Boston, a boy's testicles form in his abdomen alongside the kidneys. By birth, his testicles have moved down (descended) into his scrotum. If one or both don’t “drop,” he has a painless condition called undescended testicles or cryptorchidism.
Testicles produce sperm and testosterone. The American Urology Association Foundation (AUAF) wrote the scrotum keeps testicles in a cooler environment than the body, because sperm can’t develop at body temperature.
During childhood, sperm work to mature by puberty. If the testicles are undescended, sperm doesn’t mature.
The National Institutes of Health (NIH) said usually there aren’t symptoms, except that one or both of the testicles can’t be found in the scrotum. Children’s Hospital Boston continued if both testicles are undescended, the scrotum looks unusually small and flat. If only one is affected, the scrotum may look lopsided.
In most cases, said AUAF, it’s unknown what causes undescended testicles. Some believe the testicles aren’t normal in the first place.
In some cases, there’s a mechanical problem where they descend but miss the scrotum and end up adjacent to it. Or hormones may be insufficient to normally stimulate the testicles.
Undescended testicles are fairly common in premature infants, wrote NIH. It occurs in about 3-4 percent of full-term infants. Most of the time, testicles descend by the time boys are 9 months old.
KidsHealth.org stated treatment is important because testicles that remain undescended may be damaged, which could affect fertility or lead to other medical problems.
Bringing the testicle into the scrotum improves sperm production, said NIH, and increases the odds of good fertility.
AUAF wrote that testicles that don’t descend into the scrotum are associated with a higher risk of testicular cancer in adulthood. Many times undescended testicles can also be associated with hernia.
Undescended testicles may be more vulnerable to injury or testicular torsion (when blood supply is cut off) said KidsHealth.org. An asymmetrical or empty scrotum may cause embarrassment.