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. There may be agenesis or hypoplasia, which is rare, or hydronephrosis.
Vesicoureteral reflux is common.
The bladder is generally dilated, and the trabecula are thinned. A patent urachus may allow the bladder to decompress. The prostate is often hypo plastic with compensatory dilatation of the posterior urethra at that level. 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. From the Illustrated Encyclopedia of Human Anatomic Variation.