Fetal urinary tract obstruction and trisomy 18 mosaicism. A case report

Routine ultrasound examination has led increasingly to antepartum detection of fetal anomalies. Management decisions remain difficult, however, because information on the presence of other anomalies is frequently unobtainable. A case of fetal urinary tract obstruction, although apparently an isolated defect, proved to be associated with a lethal chromosome abnormality, trisomy 18 mosaicism.