OUTCOME OF SINGLETON PREGNANCIES WITH SEVERE OLIGOHYDRAMNIOS IN THE 2ND AND 3RD TRIMESTERS

We evaluated the significance of severe oligohydramnios, or anhydramni os, in the second and third trimesters, by determining the range of et iologies as well as the differences in fetal and neonatal outcome. All prenatal ultrasound results on pregnancies found to have severe oligo hydramnios over a 7.5-year period at 13-42 weeks' gestation were retro spectively collected. Follow-up results were obtained from review of m edical records, autopsies and pathology reports. A total of 250 single ton pregnancies met the criteria of having severe oligohydramnios. A b imodal distribution in gestational age at diagnosis was seen, with mov e cases diagnosed at 13-21 weeks and at 34-42 weeks. Fetal abnormaliti es were present in 50.7% of those diagnosed with severe oligohydramnio s in the second trimester and in 22.1% of those in the third trimester . There were 10.2% and 85.3% survivors when severe oligohydramnios was diagnosed in the second and third trimesters, respectively. The rate of aneuploidy was at least 4.4% for the entire singleton population. A bimodal distribution of pregnancies presenting with severe oligohydra mnios represents two different naturally occurring populations in term s of both etiology and prognosis.