Prune-belly syndrome with prostatic hypoplasia, bladder wall rupture, and massive ascites in a fetus with trisomy 18.

An association has been noted between trisomy 18 and genitourinary abnormalities, with six previous reports of the prune-belly syndrome occurring in patients with trisomy 18. We have observed a 120-g fetus of 18 weeks' gestational age at autopsy in whom there was severe prune-belly syndrome and trisomy 18. Serial histologic sections and reconstruction of the lower urinary tract demonstrated severe prostatic hypoplasia with a dilated, angulated prostatic urethra. Obstruction appeared to be present at the internal sphincter as a result of loss of prostatic support of the bladder. The bladder was distended and hypertrophic, and had a disruption of its wall near the apex. Massive ascites and intraabdominal urine accumulation had produced abdominal distention and pulmonary hypoplasia. The findings in this case lend support to the concept of prostatic hypoplasia as a cause of prune-belly syndrome and to the unexplained association between trisomy 18 and genitourinary anomalies including the prune-belly syndrome.