Antepartum Spontaneous Rupture of the Intertwin-dividing Membrane in Monochorionic Diamniotic Twins; Nearly

Umbilical cord entanglement has been reported to occur in monoamniotic twins. However, it can occur in diamnionic twins due to rupture of the intertwin-dividing membrane, and is a cause for concern. A 31-year-old nullipara visited our hospital at 28+3 weeks gestation. A monochorionic diamniotic twin gestation was diagnosed ultrasonographically by visualizing a thin intertwin-dividing membrane and a single placenta. A cesarean section was performed at 35+3 weeks gestation and concordant twin fetuses with entangled umbilical cords were delivered. Gross examination revealed a single placenta with a ruptured dividing membrane. Our case, along with the other cases, confi rms that antepartum rupture of an intertwin-dividing membrane is a clinical condition that should be considered in all cases of monochorionic diamniotic twin. A careful inspection of the dividing membrane and each cord insertion site should be performed. Once the dividing membrane cannot be easily visualized, the possibility of antepartum rupture should be suspected.