Prevalence of Extraplacental Anastomoses in Monochorionic Twin Pregnancies

Abstract

Objectives: To evaluate the prevalence of extraplacental anastomoses (EPA) and the factors associated. Methods: A retrospective study including 144 placentas from monochorionic diamniotic (MCDA) twins delivering at one institution was performed. EPA were defined as any intertwin anastomosis located outside the chorionic plate on macroscopic inspection. The association with perinatal factors and with umbilical cord insertion site was analyzed. Results: The prevalence of EPA was 4.9% (7/144). Velamentous cord insertion of both twins was significantly associated with the presence of EPA in the multivariate logistic regression model (p = 0.045). Discussion: EPA was found in ≈5% of MCDA twin pregnancies.