Perinatal outcomes in monoamniotic gestations

Abstract

Objective: A comprehensive review of monoamniotic twin gestations reported between 1990 and 2002 was performed to estimate current perinatal mortality and morbidity rates, as well as the predictivevalue of an antenatal diagnosis of cord entanglement for poor obstetric outcomes.Method: A Medline literature review using the search term 'monoamniotic' and limited to articles published inthe English language between 1990 and 2002 was performed.Results: A total of 133 continuing, non-conjoined twin monoamniotic pregnancies with delivery information were identified. Perinatalloss per 2-week interval was relatively constant at 2-4% from 15 to 32 weeks. However, of the 131 fetuses reaching 33 weeks, the percentage loss significantly increased to 11.0% at 33-35 weeks and 21.9%at 36-38 weeks compared to that at 30-32 weeks. Overall perinatal mortality was 23.3%. Of all losses, 61.2% involved both twins and 38.8% involved only one fetus. Cord entanglements were documented antenatallyin 22.6% of reports. There was a statistically significant decrease in the average number of neonatal intensive care unit days for non-anomalous neonates (10.6 ± 7.7 vs. 32.6 ± 32.0), averagegestational age at the time of delivery (30.4 ± 7.6 vs. 32.6 ± 4.1), as well as a decrease in the prevalence of total (8.3% vs. 27.7%) and non-anomalous (7.0% vs. 21.6%) perinatal mortalityin pregnancies with an antenatal diagnosis of cord entanglement compared to those without the antenatal diagnosis of cord entanglement. The presence of fetal anomalies was associated with a 42.9% perinatalmortality rate.Conclusions: Contrary to previous reports, there is a significant increase in the incidence of perinatal loss beyond 32 weeks among monoamniotic twins, suggesting that deliveryafter corticosteroid therapy should be strongly considered at this gestational age.