Prune belly syndrome is a congenital disorder in which the abdomen is wrinkled at birth due to missing or weakened abdominal muscles. Some babies born with the syndrome don’t live beyond infancy, others may survive and lead relatively typical lives after treatment.

Prune belly syndrome (PBS) is also known as Eagle-Barrett syndrome. This syndrome is very rare. While the disorder affects the abdominal muscles and the stomach’s appearance, it may also lead to symptoms in other parts of the body.

Here’s more about what causes PBS, how it’s diagnosed, and how it’s treated.

PBS is a congenital disorder, which means a child is born with it. This disorder primarily affects people assigned male at birth.

The syndrome has three characteristic features, also called a triad:

  • The baby’s stomach looks prune-like — wrinkled in appearance — due to missing or weak abdominal muscles.
  • If the baby is male, the baby’s testicles don’t drop from the inside of the body to the scrotum (undescended testicles), which is the area of skin located under the penis.
  • The baby’s kidney and bladder (urinary tract system) have abnormalities.

In addition to these three features, babies born with PBS may also have issues with other systems, including:

  • lungs
  • heart
  • intestines
  • musculoskeletal system

Symptoms of PBS aren’t necessarily the same from one child to the next. However, the age of onset (when symptoms begin) is usually the same: before birth or within 4 weeks after birth.

Signs and symptoms may include:

Some babies with PBS have what’s called pseudo prune belly syndrome (PPBS).

So, what’s the difference between PBS and PPBS?

  • PBS causes bilateral issues (problems on both the right and left sides) of the urinary tract, testes, and abdominal muscles.
  • PPBS causes unilateral issues (problems on only the right or left side) of the urinary tract, testes, and abdominal muscles. Some children with PPBS may have typically placed testes or a typical abdominal wall.

Both PBS and PPBS are considered rare conditions. PPBS is considered a variant (type) of PBS and is extremely rare, with only a few cases being covered in the research literature.

PBS is something babies are born with and doesn’t develop over time or due to environmental factors. Beyond this fact, though, doctors don’t know what causes the syndrome. Researchers have investigated some possible causes, but the exact cause remains unclear.

Genetic changes

PBS may be associated with autosomal recessive disorders, which are genetic disorders where you inherit one affected gene from each parent. Other disorders that are autosomal recessive include Patau syndrome (trisomy 13), Edwards syndrome (trisomy 18), and Down syndrome (trisomy 21).

Another theory for a genetic cause for PBS suggests that it may be related to X-linked recessive or sex-limited autosomal recessive genetic factors. This is because more than 95% of people with PBS are people with XY chromosomes (typically assigned male at birth). There are twins who both have PBS, and there are multiple reports of family members who have PBS.

In X-linked recessive or sex-limited autosomal recessive genetic factors, an individual only needs one altered X chromosome to inherit the condition.

Other theories

Other theories for possible causes include changes in the fetal bladder that lead to a buildup of urine, which may prevent the growth of other parts of the urinary system and the developing muscles of the abdomen.

It can also be caused by an unidentified neurological problem that affects fetal growth and development. However, to date, the exact cause of PBS remains unknown.

There are no known risk factors for PBS. People assigned male at birth are more likely to have the syndrome than people assigned female at birth.

Beyond that, more research is needed to determine the underlying causes and risk factors.

Treatment for PBS depends on the areas affected, the severity, and your child’s age and health status.

For example, babies with mild symptoms, like UTIs, may only need antibiotics to manage their symptoms. Children may also need medications for severe constipation and respiratory infections, both of which are caused by features of the syndrome, such as a defective Valsalva maneuver and a weak cough.

Some children need surgery — sometimes multiple surgeries — to correct other symptoms, such as:

  • orchiopexy to repair undescended testicles, usually when a child is around 6 months old
  • abdominal wall reconstruction is usually performed along with other surgeries
  • urinary tract procedures, which may be performed early or delayed depending on the severity of the child’s issues
  • kidney transplant, needed in around one-third of people with PBS

The outlook for babies with PBS varies. Researchers divide the outlook into three different groups:

  • Group 1: Around 20% of babies have severe issues and may be stillborn or die in the hours and days after birth.
  • Group 2: Around 40% of babies have significant kidney abnormalities and may deal with ongoing urinary tract and other medical issues, which often require one or more surgeries and long-term care.
  • Group 3: Another 40% of babies may lead relatively typical lives with only mild renal/urinary issues.

Your child’s pediatrician may diagnose PBS after your child is born by observing the classic signs, like the wrinkled abdomen. Beyond that, imaging tests, such as ultrasound and X-ray, can help diagnose issues beneath the surface.

An intravenous pyelogram (IVP) is a test you may encounter as well. An IVP uses a dye to help map out the kidneys, their ducts, and the syndrome’s impact on this system (the genitourinary tract).

PBS may also be diagnosed before a child is born via prenatal ultrasound.

Doctors and researchers are still working to determine the exact cause of PBS. As a result, there are no known ways to prevent it.

Can people assigned female at birth have prune belly syndrome?

PBS primarily affects people assigned male at birth. However, there are a few cases (less than 5%) that have been reported in people assigned female at birth. So, it can affect both sexes.

How long does the wrinkled appearance of the belly last?

As a baby grows, the prune-like appearance of the stomach usually changes. This is because as babies grow, they gain fat deposits over the muscles of the stomach. While the belly may eventually look more typical, this doesn’t mean the syndrome has gone away.

Are people with prune belly syndrome infertile?

Research, mainly from before 1992, suggested that men with PBS were infertile. However, various procedures like sperm retrieval and IVF have allowed men with PBS to have children. More study is needed on women, but there’s at least one report of a woman with PBS having a vaginal birth.

Language matters

You’ll notice we use the term “women” and “men” in this article. While we realize this term may not match your gender experience, it’s the term used by the researchers whose data was cited. We try to be as specific as possible when reporting on research participants and clinical findings.

Unfortunately, the studies and surveys referenced in this article didn’t report data for or may not have had participants who are transgender, nonbinary, gender nonconforming, genderqueer, agender, or genderless.

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Prune belly syndrome (PBS) is a rare genetic disorder that primarily affects people assigned male at birth. Some babies born with the syndrome have severe complications, while others have only mild issues.

Researchers are still trying to determine the cause of the syndrome. If your child receives a diagnosis of PBS, your pediatrician will work with a team of doctors to provide your child with the care they need to thrive.