Prune Belly Syndrome: 5 Things to Know

Prune belly syndrome (PBS) is a rare birth defect. It affects the urinary tract, genitals and belly (abdominal wall). Babies are born with it.

1. Prune Belly Syndrome Is Rare but Can Be Deadly

PBS affects 1 in 50,000 births. Nearly all (95%) of people with PBS are males. About 1 in 5 babies born with PBS are not alive when they are born (stillborn), and 3 in 10 die of kidney failure by age 2 years. About 1,500 people under age 18 have PBS in the United States.

It is often found as early as 15 weeks in pregnancy during an ultrasound. The doctors may see a very large urine-filled bladder. However, diagnosing PBS before birth can be hard because other conditions may look like it. There is currently no definite genetic test for PBS.

When babies with PBS are born, they typically have extremely full bladders. Because urine has not been completely coming out of the baby’s body before birth, 10-20% of babies have kidney failure at birth. Because the baby’s (fetal) urine makes up the amniotic fluid, lung development may also be affected because of the decrease in amniotic fluid.

About half (40-60%) of babies born with PBS have other birth defects.

2. The Three Key Features That Are Helpful in Diagnosing PBS Are Called the Prune Belly Triad

The three features that make up the prune belly triad include:

• Wrinkled belly
• Undescended testicles
• Enlarged urinary tract (dilation of bladder, ureters and kidneys)

3. Most Babies with PBS Will Need Procedures and Several Surgeries in Their Early Childhood

The first procedure for PBS babies is draining the excess urine. Then, babies with PBS often need many surgeries. This depends on the child’s condition and the surgeon’s suggestions. Common surgeries to treat PBS include:

• Retrieving the testicles: The goal is to have both testicles down (descended) into the scrotum by age 1 year.
• Urinary tract reconstruction
• Abdominal “tummy tuck” to rebuild the belly that lacks normal muscle: This is typically done between the ages of 4 months and 1 year.

4. Children with PBS Need Lifelong Care to Keep Their Kidneys as Healthy as Possible

Historically, (67%) of individuals with PBS will go into kidney failure during their lifetime. However, proper care can hopefully prevent this. Factors that affect kidney health in children with PBS include:

• Not being able to empty their bladder because they don’t have strong abdominal muscles
• Making high amounts of diluted, water-filled urine
• Experiencing frequent urinary tract infections (UTIs)

Seeing a urology specialist regularly and being aware of any changes in urine output or infections is an important part of managing PBS. Children and adults with PBS will need a yearly ultrasound to check their bladder and kidney health. Children with PBS do not feel that their bladder is full – it is abnormal in that it doesn’t hurt. They often need to be reminded to pee (urinate) every two hours and work hard to empty their bladder completely.

5. We Are Trying to Find the Causes of PBS

My team is conducting research to find genetic causes of PBS. My current grant from the National Institutes of Health (NIH) is funding research designed to:

• Identify and study changes (mutations) or genetic changes that cause PBS
• Understand the role of a recently identified gene that might cause PBS
• Understand cellular and molecular processes in the organs affected by PBS

Because 95% of PBS patients are male, we are studying whether PBS could be caused by a gene found on the X chromosome.

We work with the Prune Belly Syndrome Network (PBSN) to find research participants and share research results with families affected by PBS. A few families have more than one family member with PBS, and studying these families is especially valuable. But we believe that working together can help provide answers for families and offer clues to future treatments.