Prune Belly Syndrome (PBS) is a rare congenital disorder that primarily affects male infants, occurring in approximately one in 30,000 to 40,000 live births. It is sometimes referred to as Eagle-Barrett syndrome or triad syndrome due to its characteristic group of three physical abnormalities. The distinctive name comes from the wrinkled, prune-like appearance of a newborn’s abdomen, caused by a lack of muscle tone in the abdominal wall. PBS presents with a wide range of severity, requiring specialized medical attention from birth.
The Classic Triad of Prune Belly Syndrome
Prune Belly Syndrome is defined by three distinct abnormalities, starting with a deficiency of the abdominal wall musculature. This absence or severe weakness of the muscles provides poor support for the torso and contributes to the wrinkled skin appearance. The lack of proper abdominal muscle function can also affect posture, movement, and the ability to cough effectively, potentially leading to respiratory issues.
The second defining feature involves significant urinary tract abnormalities, present in almost all affected individuals. These malformations typically include a large, poorly emptying bladder and dilated, twisting ureters, the tubes that carry urine from the kidneys. This condition, known as megaureter, can cause urine to back up toward the kidneys, a problem called vesicoureteral reflux. Urinary stasis increases the risk of chronic urinary tract infections and progressive damage to the kidneys.
The third component of the triad is bilateral cryptorchidism, meaning both testicles have failed to descend into the scrotum. They are typically located within the abdominal cavity or the inguinal canal. Undescended testicles increase the risk of malignancy and potential fertility issues later in life.
Causes and Development
The exact cause of Prune Belly Syndrome is unknown, but the prevailing theory suggests a problem occurs early in fetal development, likely between the sixth and tenth weeks of gestation. An obstruction in the urethra, the tube that drains urine from the bladder, causes a massive buildup of urine. The resulting pressure severely distends the bladder and urinary tract.
This extreme distension secondarily interferes with the proper development of surrounding structures. The pressure prevents the abdominal muscles from forming correctly, leading to their absence or weakness. This mechanism is also thought to hinder the normal descent of the testicles into the scrotum. While most cases are sporadic (occurring randomly), some reports in siblings suggest that genetic factors may play a role in a small number of instances.
Diagnosis and Initial Treatment Strategies
PBS is frequently detected before birth through routine prenatal ultrasound, which may reveal findings such as a distended bladder or hydronephrosis (swelling of the kidneys due to backed-up urine). After birth, diagnosis is often made based on a physical examination, noting the characteristic abdominal appearance and undescended testes. Imaging tests, such as a voiding cystourethrogram (VCUG), evaluate the severity of urinary tract malformations, looking for blockages and urine reflux.
Initial management focuses on protecting the kidneys and preventing serious infections. Prophylactic antibiotics are often started immediately after birth due to the high likelihood of urinary tract infections. Surgical interventions are tailored to individual needs and may include an abdominoplasty, a procedure to reconstruct the abdominal wall, which improves posture, breathing, and coughing ability.
For the urinary tract, a temporary measure like a vesicostomy may be performed, creating a small opening in the bladder through the abdominal wall for free drainage. More advanced procedures may involve reconstructing the ureters or bladder itself. Orchiopexy, a surgical procedure to bring the undescended testicles down into the scrotum, is typically recommended around six months of age to facilitate monitoring and reduce risks.
Long-Term Health Management and Prognosis
The long-term outlook for individuals with PBS depends on the initial function of the kidneys, with renal dysplasia severity being the main prognostic factor. Lifelong follow-up with specialists, including nephrologists and urologists, is required to monitor kidney and bladder function. Regular monitoring helps in the early detection and management of chronic kidney disease, which affects a significant portion of patients.
Chronic kidney disease can lead to the need for dialysis or kidney transplantation later in life. Individuals with a poorly functioning bladder may require clean intermittent catheterization to ensure complete emptying and reduce infection risk. Although the condition presents substantial challenges, the spectrum of severity is wide, and many individuals with milder forms can lead relatively typical lives after appropriate treatment and ongoing care.