Pregnancy outcome following ultrasound diagnosis of fetal urinary tract anomalies and/or oligohydramnios.

We have reviewed 49 pregnancies with ultrasound evidence of fetal urinary tract anomalies and/or oligohydramnios. A surprisingly large number of fetuses with urinary tract obstruction had significant other anomalies. Fetuses with urinary tract obstruction, but a normal amount of amniotic fluid, did well without in utero intervention; however, those with oligohydramnios or polyhydramnios fared poorly. Longer periods of oligohydramnios in fetuses with urinary tract obstruction seemed to be associated with pulmonary hypoplasia and renal dysplasia. Oligohydramnios without urinary tract obstruction complicated 28 pregnancies; there were only 10 survivors. Diagnostic pitfalls are described.