Two separate placental masses on ultrasound do not always indicate a dichorionic pregnancy.

Monochorionic pregnancies are associated with a higher risk of perinatal morbidity and mortality than dichorionic pregnancies. Early determination of chorionicity by an ultrasound exam between 11+0 and 14+0 weeks' gestation (WG) is essential for the subsequent management of twin pregnancies. The presence of the T-sign is the most specific sign for determination of monochorionicity. During the second trimester, the presence of two distinct placental masses has a lower specificity in determining the chorionicity. We report here two cases of a monochorionic pregnancy with a bipartite placenta, suggesting that a placenta with two separate masses, each with a distinct cord insertion is not always indicative of a dichorionic pregnancy.'