Prune Belly Syndrome

Original Editor - Aminat Abolade
Top Contributors - Aminat Abolade, Kim Jackson and Ravi Kumar

Introduction

Prune belly syndrome (PBS), also known as Eagle-Barrett syndrome, is a rare and complex multisystem disorder that is characterized by incomplete or absent musculature of the abdominal wall, bilateral intra-abdominal cryptorchidism, and urinary tract anomalies such as megalourethra, megacystis, hydroureteronephrosis, and renal dysplasia.

Epidemiology

Prune belly syndrome (PBS) predominantly affects male infants, with an incidence of 3.8 per 100,000 live male births in the United States. Females account for less than 5% of all PBS cases and typically present with an absent abdominal wall musculature and a dilated and abnormal urinary tract without any concurrent gonadal anomaly. A genomic mutation in the HNF1β (hepatocyte nuclear factor) transcription factor has been identified in 3% of PBS cases. HNF1β plays a crucial role in regulating gene expression necessary for mesodermal and endodermal development, and it is expressed in various tissues. Although PBS is typically considered a sporadic condition, its high concordance rate in twins (12.2 per 100,000 live births), reports of monozygotic male twins with PBS, familial case reports, and the higher incidence of PBS in males suggest a genetic contribution. However, the occurrence of both discordance and concordance for PBS in monozygotic twins suggests that genetic mutations alone cannot entirely explain the pathogenesis of the syndrome.

Clinical Presentation

Prune Belly Syndrome

Children with PBS may present with

• Wrinkled, redundant skin with bulging at the flanks due to deficiency of abdominal wall musculature
• Prematurity

• Hydroureteronephrosis - dilation and enlargement of both the ureters and the kidneys
• Pulmonary hypoplasia - underdevelopment or incomplete growth of the lungs
• Cryptorchidism - One or both testicles fail to descend properly into the scrotum
• Vesicoureteral reflux – an abnormal flow of urine from the bladder back into the ureters and potentially reaching the kidneys
• Megaureter/megacystis - abnormally enlarged or dilated ureter/bladder
• Clubfoot
  

Classification of Prune Belly Syndrome

Woodard proposed a classification system for Prune Belly Syndrome (PBS) that divides children with PBS into three major categories based on their antenatal and anatomical features:

Category I: Children in this category exhibit pronounced oligohydramnios resulting from renal dysplasia and/or outlet obstruction, leading to severe pulmonary hypoplasia and skeletal abnormalities. These neonates often have a poor prognosis and may die within a few days of birth. They may exhibit Potter's facies, which are characterised by micrognathia, wide-set eyes, flattened palpebral fissures, prominent epicanthus, flattened nasal bridge, low-set ears lacking cartilage, and skeletal deformities. Urethral atresia cases are typically classified as Category I.

Category II: Children in this category have the classic features of PBS, and their prognosis is influenced by the degree of renal dysplasia present. There is a wide variation in the degree of renal dysplasia in this category, with severe forms requiring early dialysis. Pulmonary hypoplasia is not a prominent feature.

Category III: Children in this category exhibit mild triad features or incomplete forms of PBS, and their renal function is usually normal or mildly impaired. They do not exhibit pulmonary insufficiency.

Diagnosis

Ultrasound examination at 11 to 14 weeks of gestation can potentially identify prune belly syndrome. Ultrasound findings suggestive of prune belly syndrome include hydroureter, bilateral hydro nephrosis, urinary bladder wall thickening, musculoskeletal abnormalities, and oligohydramnios. If the manifestations of PBS are not markedly severe, it may not be feasible to detect the condition prenatally, and diagnosis can only be established postnatally (after birth) due to the presence of similar characteristics in various urinary malformations.

Management / Interventions

The management of Prune Belly Syndrome (PBS) in children poses a significant challenge, necessitating timely and specialized care involving a multidisciplinary team, including a neonatologist, physiotherapist, urologist, and nephrologist, with additional involvement of cardiologists and orthopaedic specialists when indicated. A comprehensive approach to care is essential to address the complex medical needs associated with PBS and ensure optimal outcomes for affected children.

Surgical Management

The surgical intervention for Prune Belly Syndrome (PBS) requires an individualized approach that considers the specific characteristics of each case, as well as the timing and methodology of the surgical procedure. The surgical management of PBS includes orchiopexy (a procedure to help the testicles descend into the scrotum), abdominal wall reconstruction (abdominoplasty), ureterostomy, urinary tract reconstruction, or kidney transplantation.

Physiotherapy Management

• Chest physiotherapy and postural drainage: To help manage respiratory involvement in the form of aplasia and hypoplasia of the lungs, flaring of the ribs, and narrowing in the transverse diameter of the chest leading to inability to cough, pooling of secretions, recurrent respiratory tract infections, and pneumonia.
• Customized trunk compressive garments: To enhance Valsalva activities and provide support to the musculature of the trunk core, thereby facilitating the child's ability to sit upright and develop fine motor skills.
• Neuro-developmental therapy
• Therapeutic exercises.
• Orthotic devices or assistive devices may be utilized to optimize mobility and posture.
• Bladder and Bowel Management

Differential Diagnosis

• Pseudo–prune belly syndrome
• Posterior urethral valves
• Chronic renal failure
• Urorectal Septum Malformation Sequence