Prune belly syndrome and fetal ascites.

A case of prune belly syndrome (PBS) in a 22 week male fetus is described. All the features characteristic of the syndrome were present: absence of abdominal muscle; dilatation of the bladder, ureters, and renal pelves; and undescended testes. In addition, there was marked ascites. The rectus abdominis muscles were entirely absent whereas other abdominal muscles were only absent centrally. Between regions of normal and absent musculature muscle fibers were sparse, enlarged, frequently disrupted, and mostly in the myotubule stage. The prostate was thin-walled and its urethra greatly expanded. The testes lay close to the corresponding ureters and each ductus deferens was only partially present. It is considered that prostatic dysgenesis and fetal ascites are key factors in the causation of PBS.