What are undescended testicles?
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.
Symptoms of undescended testicles
Undescended testicles do not cause pain or any other symptoms. In some cases there can be physical signs, such as not being able to feel the testicles.
Undescended testicles are broadly grouped into two categories:
- palpable undescended testicles (the testicle(s) can be felt during a physical examination)
- unpalpable undescended testicles (the testicle(s) cannot be felt during a physical examination)
Palpable undescended testicles
Palpable undescended testicles are the most common type and account for 80% of all cases.
In most cases, palpable undescended testicles are located just above the scrotum. They are lodged at the end of the inguinal canal (a channel that runs from the lower abdomen down towards the penis and scrotum).
Unpalpable undescended testicles
There are three main types of unpalpable undescended testicles.
Abdominal or intra-abdominal
An abdominal, or intra-abdominal, testicle occurs when the testicle is located inside the abdomen, usually close to the upper opening of the inguinal canal. This accounts for 40% of cases.
An inguinal testicle is a testicle that has moved into the inguinal canal, but has not moved far enough down towards the scrotum to be detected during a physical examination. This type accounts for 40% of cases.
Atrophic or absent
An atrophic testicle is a testicle that is abnormally small. An absent testicle is where one testicle has never been created during a baby’s development inside the womb. This type accounts for 20% of cases.
Both atrophic and absent testicles can have a variety of causes.
Read more about the causes of undescended testicles.
Causes of undescended testicles
Undescended testicles are caused by something that interrupts the normal development of the testicles.
In normal development, once the testicles have formed they stay inside the baby’s abdomen until the seventh month of pregnancy. It is then thought that hormones "activate" the descent of the testicles. They move slowly down from the abdomen, through the inguinal canal and into the scrotum. In most cases, the testicles should be in place shortly before, or soon after, birth.
In males, at around the ninth week of pregnancy, the male sexual chromosomes trigger the production of a hormone called testosterone. Testosterone triggers the development of the male genitals. At this stage, problems relating to absent, or atrophic, testicles can arise. For example, the penis may develop normally but, for unknown reasons, the testicles do not.
Alternatively, abnormal genital development may happen due to a rare condition, such as androgen insensitivity syndrome. This is where the body is partially insensitive to hormones, such as testosterone, which results in the baby being born with ambiguous genitalia (the genitals have male and female characteristics).
In most cases of undescended testicles, something seems to interrupt the descent of one or both testicles, and it (or they) remain inside the abdomen or the inguinal canal.
It is not known exactly why this happens, but several possibilities have been identified that increase this risk. These are outlined below.
The known risk factors for undescended testicles are as described below.
- Low birth weight: boys with a birth weight of less than 2.5 kg (5.5lb) are two-to-three times more likely to be born with undescended testicles than the population at large.
- Being born prematurely: the earlier a boy is born, the more likely he will be born with undescended testicles. Read more about [premature labour and birth].
- Having a family history of undescended testicles: having an older brother with undescended testicles means that a boy is three times more likely to be born with the condition compared with the general population.
- Maternal diabetes: women who have type 1 and type 2 diabetes are twice as likely to give birth to a boy with undescended testicles compared with women who do not have diabetes.
- Smoking by the mother during pregnancy.
- Alcohol consumption by the mother during pregnancy (see below).
Testicular dysgenesis syndrome
Over the last 30 years, there has been a marked increase in the number of cases of undescended testicles in Western countries. Rates of three other conditions that affect the male genitals have also increased. These are:
- a low sperm count
- testicular cancer
- hypospadias: a condition where the urethra (the tube in the penis through which urine passes) is not in the correct position
Some researchers believe that all these conditions, along with undescended testicles, could be interrelated. Rather than being separate conditions, they could be different forms of a single underlying syndrome that is known as "testicular dysgenesis syndrome (TDS)".
If TDS exists, it may be caused by exposure to chemicals during pregnancy that disrupt the normal balance of hormones. This may interfere with the normal development of the male genitals.
Chemicals that are known to disrupt hormonal balance are called endocrine disruptors.
Examples of endocrine disruptors include:
- some types of pesticide
- polychlorinated biphenyls (PCBs): a chemical compound that is used as a coolant
- dibutyl phthalate: a chemical that is used to manufacture cosmetics, such as nail polish
In most countries, including the UK, many endocrine disruptors such as PCBs have been withdrawn due to a link with health problems. But there are still concerns that people may still be exposed to endocrine disruptors through contamination of the food chain.
The World Health Organization (WHO) has done extensive research to find out whether exposure to endocrine disruptors is causing the rise in conditions that affect male fertility.
Researchers have concluded that direct exposure to high levels of endocrine disruptors can negatively affect human health and male fertility.
But there is not yet enough evidence to prove a definite link between health problems and indirect exposure to low levels of endocrine disruptors. Indirect exposure is the type of exposure that occurs if the food chain is contaminated.
Diagnosing undescended testicles
Undescended testes are usually diagnosed either soon after the baby is born or during a routine check-up when they are six-to-eight weeks old.
The first stage in diagnosing undescended testicles is to carry out a physical examination to see whether the testicles can be felt near the scrotum (whether they are palpable).
The physical examination can sometimes be difficult, and your doctor may refer your child to a paediatric urologist to help with getting the right diagnosis.
If the examination reveals that both testicles are undescended and unpalpable (cannot be felt), then blood tests can be used to check whether hormonal problems may have disrupted the testicles' normal development.
A procedure called a diagnostic laparoscopy is usually needed to find an unpalpable testicle. Diagnostic laparoscopy is a type of "keyhole surgery" that uses an instrument called a laparoscope.
A laparoscope is a small, flexible tube that contains a light source and a camera. The camera relays images of the inside the abdomen, or pelvis, to a television monitor.
Depending on where the testicle is located, it may be possible to perform surgery immediately in order to reposition the testicle into the scrotum.
Read more about how undescended testicles are treated.
How to treat undescended testicles
In many cases, the testicle(s) will descend into the scrotum by the time your child is four months old. If the testicle(s) do not descend by this time, treatment is usually recommended.
For most cases of undescended testicle(s), surgery to reposition the testicle(s) into the scrotum is usually recommended. This type of surgery is known as an orchidopexy.
Exactly when the operation is carried out will depend on your child’s health. Ideally, surgery should be performed between the age of six months and two years. This is because waiting longer than two years has been shown to increase a boy’s risk of developing fertility problems or testicular cancer.
Increasingly, orchidopexies are performed using a type of keyhole surgery known as a laparoscopy. This type of surgery causes less post-operative pain and has a faster recovery time than open surgery.
During the procedure, the surgeon makes a small incision (cut) in your child’s abdomen, before passing small surgical instruments through the incision in order to free the testicle from the surrounding tissue.
The testicle is then moved down the inguinal canal and repositioned in the scrotum using a second incision. The inguinal canal is then usually sealed to prevent the testicle from moving back out of the scrotum.
An orchidopexy is performed under a general anaesthetic, which means that your baby will not feel any pain during the operation. In most cases, surgery can be performed as day surgery, so your child will be able to return home on the same day.
Your child may feel unwell for the first 24 hours after surgery. Feelings of nausea are a common side effect of general anaesthetic. They are nothing to worry about.
The following advice should help to speed up your child’s recovery time and reduce their risk of having any post-operative complications.
- Your child will need to have regular pain relief for three days after the operation. Activities such as playing games, watching television and reading together may help to keep his mind off the pain.
- Encourage (but don't force) your child to drink plenty of fluids.
- Your child’s groin area may feel sore for a while after the operation. Letting him wear loose-fitting clothing will help.
- Keep the operation site clean and dry, and avoid soaking the area during a shower or bath.
- Your child should not ride a bicycle or use "sit-on" toys, for one month after the operation. This is to prevent the testicles travelling back up into the abdomen.
Be alert for any signs that the site of the surgery has become infected. These include:
- Your child being in a lot of pain, and the prescribed pain relief not working.
- Your child having a high temperature (fever) of 38C (100.4F) or above.
- The site of the surgery being red, inflamed or feeling hotter than the surrounding area.
- A discharge of fluid, or pus, appearing from the site of the surgery.
If you notice any of these signs and symptoms, contact your doctor as soon as possible for advice.
Results of surgery
As a general rule, the closer the testicle is to the scrotum, the more likely surgery will be successful.
The success rates for treating palpable testicles that are located near the scrotum are estimated to be between 80%-90%.
The success rate for treating unpalpable testicles is between 75%-90%, depending on where the testicle is located. If surgery fails, further surgery may be needed to reposition the testicle in the scrotum.
Complications of surgery
As with any type of surgery, an orchidopexy carries the risk of causing complications.
The most serious complication of surgery is testicular atrophy. The blood supply cannot sustain the testicle in its new position, which causes the testicle to wither away. This is known as testicular atrophy, and it occurs in an estimated 5% of cases.
If testicular atrophy occurs, your child’s fertility should be unaffected as long as he still has one healthy testicle.
If necessary, cosmetic surgery can be performed to remove the affected testicle and place an artificial implant in your child’s scrotum.
Damage of the vas deferens
Another possible complication of an orchidopexy is that the vas deferens may be accidentally damaged.
The vas deferens is a tube that connects the testicle to the urethra. The urethra is the tube through which the sperm passes when a man ejaculates. Damage to the vas deferens occurs in an estimated 1% of cases.
If the vas deferens is damaged during surgery, further surgery is usually needed to repair it. If left untreated, it can cause fertility problems in later life.
Alternatives to surgery
An alternative to surgery is to use synthetic hormones that encourage the testicle move out of the abdomen and down into the scrotum.
Hormone therapy is usually only recommended if your child’s testicle(s) are close to the scrotum. This is because the treatment is usually ineffective in treating unpalpable testicles that are located in the inguinal canal or abdomen.
Hormone therapy may also be recommended if both testicles are undescended and blood tests have shown that this is due to underlying problems with their hormones.
If hormone therapy is unsuccessful as a treatment, then surgery will usually be required.