Undescended testicles are a common childhood condition where a boy is born without one or both testicles in their scrotum.
The medical term for having one or two undescended testicles is cryptorchidism.
The scrotum and testicles
The scrotum is a small sac of skin that hangs underneath the penis. It holds the testicles in place.
The testicles are the two oval-shaped male sex organs that sit inside the scrotum on either side of the penis.
Testicles are an important part of the male reproductive system as they produce sperm and the hormone testosterone, which contributes to male sexual development.
The development of the testicles
During pregnancy, the testicles form inside the baby's abdomen (the area of the body that contains the stomach) before slowly moving down into the scrotum as the baby develops. The testicles are usually in place by the eighth month of pregnancy.
For reasons that are still unclear, one or both testicles sometimes do not move into the scrotum by the time the baby is born. Although the exact cause is not known, there are some theories as to why this happens.
Read more about the causes of undescended testicles.
Diagnosing undescended testicles
Having undescended testicles does not present any immediate health problems, and it is painless. It may be more obvious in some children than others.
Read more about the symptoms of undescended testicles.
Undescended testicles are usually diagnosed during a physical examination soon after a baby is born. In some cases further tests are needed to determine the position of the testicle(s).
Read more information about how undescended testicles are diagnosed.
Should undescended testicles be treated?
In many cases, the testicle(s) will descend into the scrotum some time during the first four months of the baby's life.
If the testicle(s) do not descend by this time, treatment is usually recommended. This is because boys with undescended testicles:
- may have fertility problems in later life
- have an increased risk of developing testicular cancer, although this risk is very small (an estimated 0.1%-0.25% chance)
- may have problems with their self-esteem and body image if they feel they are "missing" one or both of their testicles
Treatment options include:
- using artificial hormones to stimulate the descent of the testicle(s)
- using a type of surgery, known as an orchidopexy, to move the testicle(s) into the correct position inside the scrotum
An orchidopexy is the most common treatment and is a relatively straightforward operation that is known to have a good success rate.
It is usually carried out when your child is between six months and two years old. If the condition is treated at an early age, the boy's fertility should be unaffected.
Read more information about treating undescended testicles.
How common are undescended testicles?
Undescended testicles are one of the most common congenital conditions that affect boys. Congenital means that the condition is present at birth. It is estimated that 3%-5% of newborn boys have undescended testicle(s).
In around 80% of cases, only one of the testicles is affected. Most cases will resolve without treatment, although a small number of boys (0.7%-1%) have testicles that stay undescended into adulthood unless treated.