Prune belly syndrome

Overview

Prune belly syndrome (PBS), also known as Eagle–Barrett syndrome, is a rare congenital disorder characterized by a triad of abnormalities: absence or severe underdevelopment of abdominal muscles, bilateral undescended testicles (cryptorchidism) in males, and urinary tract malformations. The condition gets its name from the wrinkled appearance of the abdominal skin, which resembles a prune due to the lack of underlying muscle tone. Prune belly syndrome primarily affects males—over 95% of cases—though it can also occur in females, usually with different urogenital abnormalities. The severity of PBS varies widely, ranging from mild urinary issues to life-threatening complications involving kidney function and lung development.

Causes

The exact cause of prune belly syndrome remains unknown, but several theories have been proposed:

• Urinary tract obstruction hypothesis: An early obstruction in the fetal urinary tract may lead to bladder enlargement, causing secondary abdominal muscle stretching and damage.

• Mesodermal defect theory: A developmental abnormality in the lateral plate mesoderm may impair the formation of both abdominal muscles and the urinary tract.

• Genetic factors: While most cases are sporadic, familial occurrences and associations with chromosomal abnormalities suggest a potential genetic component.

• Testosterone-related developmental disruption: The absence of normal androgen action may explain the high prevalence of cryptorchidism and other genitourinary anomalies in males.

Despite these theories, PBS is generally considered a multifactorial disorder involving both genetic susceptibility and in utero environmental influences.

Symptoms

The hallmark symptoms of prune belly syndrome involve the genitourinary system and musculoskeletal abnormalities. Severity can range from minor urinary tract dilation to profound kidney dysfunction and respiratory compromise.

Classic Triad of Features

• Abdominal muscle deficiency: Weak or absent abdominal muscles cause a wrinkled, sagging appearance and poor muscle tone

• Urinary tract abnormalities: May include enlarged bladder, ureteral dilation (megaureters), hydronephrosis, and vesicoureteral reflux

• Cryptorchidism: Bilateral undescended testicles in nearly all affected males

Additional Features

• Recurrent urinary tract infections (UTIs)

• Bladder dysfunction or incontinence

• Kidney dysfunction or chronic kidney disease

• Pulmonary hypoplasia due to oligohydramnios in utero

• Skeletal anomalies, such as scoliosis or joint contractures

• Delayed motor development due to weak abdominal musculature

In severe cases, PBS may be diagnosed prenatally due to abnormal ultrasound findings, including a distended bladder and reduced amniotic fluid.

Diagnosis

Prune belly syndrome is typically diagnosed based on clinical examination and imaging studies. It may be suspected prenatally or confirmed postnatally.

Prenatal Diagnosis

• Ultrasound: Can detect signs such as enlarged bladder, oligohydramnios, hydronephrosis, and underdeveloped abdominal wall muscles

• Fetal MRI: May provide additional information about organ development and guide perinatal planning

Postnatal Diagnosis

• Physical examination: Identifies abdominal wall laxity, undescended testes, and a wrinkled abdomen

• Ultrasound of kidneys and bladder: Assesses the degree of urinary tract involvement

• Voiding cystourethrogram (VCUG): Evaluates bladder function and detects vesicoureteral reflux

• Renal function tests: Monitors creatinine and blood urea nitrogen levels

• Genetic testing: May be considered in cases with additional anomalies or suspected syndromic associations

Treatment

Treatment of prune belly syndrome is tailored to the severity of symptoms and typically requires a multidisciplinary team, including pediatric urologists, nephrologists, and surgeons. Management focuses on preserving kidney function, correcting anatomical defects, and improving quality of life.

Medical Management

• Antibiotic prophylaxis: Used to prevent urinary tract infections

• Bladder management: Includes catheterization, timed voiding, or medications to improve bladder emptying

• Monitoring renal function: Routine blood work and imaging to assess kidney health

Surgical Treatment

• Orchiopexy: Surgical placement of undescended testes into the scrotum

• Abdominoplasty: May improve appearance and support abdominal function

• Urological reconstruction: Includes procedures to correct ureteral dilation, reflux, or bladder outlet obstruction

• Kidney transplantation: Required in severe cases of end-stage renal disease

Supportive Therapies

• Physical therapy to improve core strength and mobility

• Psychological support for body image and self-esteem issues

• Genetic counseling for families

Prognosis

The prognosis of prune belly syndrome varies significantly based on the severity of urinary tract involvement and associated complications. In mild cases, individuals may lead relatively normal lives with appropriate medical care and monitoring. However, severe cases—especially those with early kidney damage or respiratory compromise—carry a higher risk of morbidity and mortality, particularly in infancy.

With advances in prenatal diagnosis, surgical techniques, and renal care, many individuals with PBS can achieve improved outcomes and long-term survival. Lifelong follow-up is often necessary to manage urologic and renal complications and support healthy development.