Prune Belly Syndrome Network, Inc.

Definition:

Also known as Eagle-Barrett syndrome, the Prune Belly syndrome consists of a triad of features:

1. Anterior abdominal wall: musculature is deficient or absent.
2. Urinary tract anomalies (mega-ureters, large bladder).
3. Bilateral cryptorchidism (undescended testicles).

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Medical Glossary:

To look up the medical definitions, click here

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General:

The incidence of prune belly syndrome is 1 in 40,000 live births; 95% of cases occur in males. In the past, it was suggested that the abdominal wall was deformed by pressure from a distended bladder due to bladder outlet obstruction in utero. Currently it is thought that prune belly syndrome is a multisystem disease complex which derives from a primary defect in mesodermal development.

The major prognostic factor is the degree of dilation of the urinary tract; 20% of patients are stillborn, 30% die of renal failure or urosepsis within the first two years of life, and the remaining 50% have varying degrees of urinary pathology.

 

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Imaging:

Renal abnormalities vary widely. There may be agenesis or hypoplasia, which is rare, or hydronephrosis. On IVP, 80% of patients have evident tortuous ureters with dilatation distally. Vesicoureteral reflux is common. The bladder is generally dilated, and the trabecula are thinned. A patent urachus may allow the bladder to decompress.

The urethra is occasionally obstructed; this feature is seen typically in infants who die early. The prostate is often hypo plastic with compensatory dilatation of the posterior urethra at that level. The anterior urethra may also be dilated (megalourethra).

 

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Etiology:

Is generally unknown but there are 2 hypotheses:

1. Urinary Tract Obstruction - hypo plastic or dysplastic prostate causes an obstruction of the urethra creates a urinary tract obstruction leading to overdistension of the bladder and the upper urinary tract stretches the abdominal wall and causes damage to the abdominal musculature and interferes with the descent of the testicles.
2. Primary Mesodermal Developmental Defect - an insult between 6 and 10 weeks gestation which disrupts the development of the lateral plate mesoderm from which arises both the abdominal wall, genitourinary tract including the prostate.

Pathology:

1. Abdominal Musculature

Myopathy

from mild hypoplasia to agenesis of the muscular layer

patchy and asymmetrical

lower and medial aspects most affected

Appearance

initially wrinkled

later "pot belly" appearance

2. Urinary Tract Anomalies

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

Prostate

lack of prostate differentiation

hypoplastic

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

Ureters

hydro- or megalo-ureter with characteristic marked dilatation, tortuous, and elongated

dilatation is segmental with segments of normal caliber

distal ureter most severely affected

diminished effective peristalsis in affected portions

vesicoureteral reflux present in most

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

Cryptorchidism

testicles usually intra-abdominal at the sacroiliac level

complications are infertility and azospermia

also at risk for testicular malignancy

3. Respiratory - classified into 2 groups based upon extent of injury:

Pulmonary Hypoplasia

due to oligohydramnios

associated with pneumothorax and; pneumomediastinum

usually leads to respiratory failure and death in the newborn period

Recurrent Lobar Atelectasis and Pneumonia

characteristic thoracic deformity with rib flaring

decreased AP diameter of chest

impaired diaphragmatic function and cough mechanism due to a lack of abdominal wall muscle for forced end-expiration

4. Cardiovascular (in 10% of cases)

ASD - atrial septal defect
PDA - patent ductus arteriosis
TOF - tetralogy of Fallot
VSD - ventricular septal defect

5. Gastrointestinal

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

6. Musculoskeletal (in 20% to 50% of cases)

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