Amnion-chorion separation after 17 weeks' gestation

OBJECTIVE: To evaluate the cause of and perinatal outcomes of amnion-chorion separation that is apparent sonographically after 17 weeks' gestation. METHODS: We searched our ultrasound database over 7 years for information on pregnant women who had live fetuses and complete separation between amnion and chorion that persisted beyond 17 weeks' gestation. For inclusion in the study, the women had to have amnion separated from chorion on at least three sides of the gestational sac. Medical records were reviewed for whether women had amniocenteses, results of the amniocenteses, and outcomes of the pregnancies. RESULTS: Of 15 pregnant women with live fetuses, ten had amniocenteses before identification of amnion-chorion separation and five did not. Three had fetuses with Down syndrome, two of whom had amnion-chorion separation evident before amniocentesis, and all three had other sonographic findings suggestive of aneuploidy. Three fetuses died. The other pregnancies were complicated by one or more adverse events, including two fetuses with growth restriction, five preterm deliveries, two with oligohydramnios, and one with abruptio placentae. Five infants were delivered at term and are alive and well. Overall, ten of 15 pregnancies resulted in live newborns, one of whom had Down syndrome. CONCLUSION: Complete amnion-chorion separation that persisted after 17 weeks' gestation is associated with a variety of adverse perinatal outcomes, including aneuploidy.