Monoamniotic and pseudomonoamniotic twins: sonographic diagnosis, detection of cord entanglement, and obstetric management

Abstract

Objective: To assess accuracy of detecting cord entanglement in monoamniotic twins, and to describe perinatal outcomes with aggressive obstetric management.

Methods: Seven nonconjoined monoamniotic twin pregnancies and one pseudomonoamniotic twin pregnancy were diagnosed sonographically and evaluated with serial scans and cardiotocography. In the absence of other indications, patients were delivered by elective cesarean on demonstration of lung maturity at or beyond 32 weeks' gestation.

Results: Cord entanglement was diagnosed correctly in four pregnancies, missed in one, and excluded correctly in three. Four pregnancies were delivered after demonstration of pulmonary maturity, three because of premature rupture of membranes or uncontrollable preterm labor, and one because of fetal heart rate abnormality during tocolysis for preterm labor. The mean gestational age at delivery was 33.2 +/- 1.6 weeks, with birth weight 2011 +/- 262 g; all neonates were live-born. Newborn stays averaged 12.0 +/- 5.8 days for the eight neonates delivered electively.

Conclusion: Monoamniotic twin pregnancies and cord entanglement in such twins were diagnosed reliably by ultrasound. Abnormal tracings prompting cesarean delivery occurred in two of the five pregnancies with cord entanglement. Amniocentesis reflected pulmonary maturity of both twins in all pregnancies so assessed, and delivery after 32 weeks' gestation, with lung maturity, resulted in good perinatal outcomes. Statistical validity of these findings is limited by our small sample size.