Management of monoamniotic twin pregnancies: a case series and systematic review of the literature

Objectives To review the experience of the University of Toronto Perinatal Complex, Ontario, Canada concerning antenatally diagnosed monoamniotic twin pregnancies; and to compare our results with cases reported in the literat ure with respect to antenatal surveillance and perinatal outcome. Methods A retrospective chart review of all twin gestations from 1993 to Ap ril 2000 was performed. A systematic review of the literature, 1966 to Apri l 2000, of perinatal outcome in monoamniotic twin pregnancies was undertake n. Setting All monoamniotic twin gestations at the University of Toronto. Results Case-series: 25 prenatally diagnosed monoamniotic twin pregnancies were identified. Seven pregnancies were affected by fetal anomalies. One fe tus died at 29 weeks. Neonatal complications occurred below 33 weeks of ges tational age and were related to immaturity. Systematic review of the liter ature: 49 studies met our selection criteria and reported 88 cases diagnose d antenatally. Fourteen pregnancies were affected by major congenital anoma lies. Twenty fetuses died after 24 weeks of gestation. Neonatal complicatio ns varied widely in severity and depended on gestational age at birth. The risk of intrauterine fetal death was 10% at the University of Toronto and 1 2% in the review of the literature. Discussion Our experience, the largest so far, suggests that regular fetal surveillance and appropriate steroid administration leads to a good perinat al outcome. The risk of fetal death (10%-12%) is lower than the previously quoted risk of 30%-70%. A careful review of obstetric interventions and fur ther work examining outpatient surveillance of monoamniotic twin pregnancie s are needed. The best treatment of monoamniotic twin pregnancies can only be determined by randomised trials.