The sonographic evaluation of fetal anomalies in oligohydramnios between 16 and 30 weeks gestation.

The sonograms of all patients with oligohydramnios between 16 and 30 weeks gestation seen over a 4-year period were reviewed to determine (1) whether sonographically detectable fetal anomalies were present, and (2) when these anomalies were present, how this information was used in maternal fetal management. Cases of ruptured membranes and fetal demise were excluded from the study. Sixteen patients with severe oligohydramnios were identified. On postmortem examination, nine had urinary tract anomalies, one had evidence of a chronic intrauterine infection, and four had no anomalies. There were only two neonatal survivors: one had no anomalies while the other had posterior urethral valves. These findings confirm that second trimester oligohydramnios has a poor prognosis and is often associated with anomalies of the urinary tract. Sonography aids in the clinical management of such patients.