PRUNE BELLY SYNDROME
 
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PRUNE BELLY SYNDROME

 

DEFINITION:

A disorder characterized by the triad of abdominal musculature deficiency, anomalous development of the urinary tract, and bilateral cryptorchidism.

EPIDEMIOLOGY:

  • incidence: 1/40,000 live births
  • age of onset:
    • newborn
  • risk factors:
    • sporadic
    • M > F (20:1)

PATHOGENESIS:

1. Background

  • etiology is unknown but there are 2 hypotheses:

1. Urinary Tract Obstruction

  • (hypoplastic or dysplastic prostate) -> obstruction of the urethra -> urinary tract obstruction -> overdistension of the bladder and upper urinary tract -> stretches abdominal wall -> damages abdominal musculature and interferes with the descent of the testicles

2. Primary Mesodermal Developmental Defect

  • an insult between 6-10 weeks gestation -> disrupts the development of the lateral plate mesoderm from which arises both the abdominal wall (derivative of the 1st lumbar myotome and genitourinary tract (plus prostate)

PATHOLOGY:

1. Abdominal Musculature

1. Myopathy

  • from mild hypoplasia to agenesis of the muscular layer
  • patchy and asymmetrical
  • lower and medial aspects most affected

2. Appearance

  • initially wrinkled
  • later "pot belly" appearance

2. Urinary Tract Anomalies

1. Urethra and Prostate

1. Urethra

  • often widely dilated
  • may be an area of abrupt narrowing distal to dilatation but urethral stenosis or atresia is rare with only 25% showing urethral obstruction at birth

2. Prostate

  • lack of prostate differentiation -> hypoplastic

2. Bladder

  • markedly enlarged capacity with thickened wall
  • may show an "hourglass configuration" on voiding cystogram
  • lateral displaced ureteral orifices in 70% of patients
  • most capable of emptying completely but may be a significant residual in some
  • apex may be attached to umbilicus with patent urachus at times

3. Ureters

  • hydro- or megalo-ureter - characteristic marked dilatation, tortuous, and elongated
  • dilatation is segmental with segments of normal calibre
  • distal ureter most severely affected
  • diminished effective peristalsis in affected portions
  • vesicoureteral reflux present in most

4. Kidneys

  • may be dysplastic, cystic, hypoplastic or grossly hydronephrotic
  • prognosis may depend on degree of kidney damage
    • chronic UTI and obstructive uropathy may lead to ESRF

3. Cryptorchidism

  • testicles usually intra-abdominal at the sacroiliac level
  • complications:
    • infertility and azospermia as the rule
    • at risk for testicular malignancy

4. Other Manifestations

1. Respiratory

  • classified into 2 groups based upon extent of injury:

1. Pulmonary Hypoplasia

  • due to oligohydramnios
  • associated with pneumothorax & pneumomediastinum
  • usually leads to respiratory failure and death in the newborn period

2. Recurrent Lobar Atelectasis and Pneumonia

  • characteristic thoracic deformity with rib flaring and decreased AP diameter of chest leads to impaired diaphragmatic function and cough mechanism due to a lack of abdominal wall muscle for forced end-expiration

2. Cardiovascular (in 10% of cases)

  • ASD, PDA, ToF, VSD

3. Gastrointestinal

  • gastroschisis
  • imperforate anus
  • malrotation with volvulus (due to unattached cecum)

4. Musculoskeletal (in 20-50% of cases)

  • talipes equinovarus (club foot)
  • congenital dislocation of the hips
  • pectus excavatum or carinatum
  • others: arthrogryposis, distasis of pubis, polydactyly, scoliosis, skin dimples, torticollis

CLINICAL FEATURES:

1. Category I

  • oligohydramnios
  • typical external features with Potter facies
  • severe pulmonary hypoplasia with marked dilatation of the urinary tract and severe renal dysplasia
  • 33% are stillborn or die within the first weeks of life
  • only occurs in males

2. Category II

  • typical external features without Potter facies
  • diffuse dilatation of the urinary tract with less severe renal dysplasia
  • survival beyond the newborn period

3. Category III

  • external features mild or incomplete
  • mildly dilated urinary tract with normal renal parenchyma

INVESTIGATIONS:

1. Serum

  • electolytes, BUN, creatinine

2. Imaging Studies

1. Renal

  • ultrasound
  • voiding cystogram
  • renal scintigraphy

2. Antenatal Ultrasound

  • has detected anomalies as early as 20 weeks gestational age

MANAGEMENT:

1. Category I

1. Palliative

  • corrective surgery not an option

2. Category II

1. Supportive

  • moniter and treat recurrent UTI's
  • moniter renal function

2. Corrective Surgery

  • temporary drainage procedures
    • cutaneous pyelostomies, vesicostomies
  • reconstructive surgery
    • transurethral urethrotomy
    • reimplantation of ureters onto bladder
    • cystoplasty to reduce size of bladder
    • to abdominal wall
  • renal transplantation
    • for ESRF
  • bilateral orchiopexy in 1st year of life

3. Category III

1. Supportive

  • moniter and treat recurrent UTI's
  • moniter renal function

2. Corrective Surgery

  • not required

 

 

 

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