Pitfalls in assessing chorioamnionicity: novel observations and literature review

Accurate diagnosis of chorioamnionicity in multiple pregnancies is the key to appropriate clinical management of multiple gestation. Although prenatal ultrasound assessment of chorioamnionicity is well established and highly accurate if performed in early pregnancy, exceptions and artifacts arise from anatomic variations in multiple pregnancies and unusual sonographic features do exist. We have summarized our own experiences and reports from the literature on these pitfalls as follows: (1) Discordant fetal sex in monochorionic pregnancies due to sex chromosome abnormalities, genital malformation in one fetus, or dizygotic twins forming a monochorionic placenta; (2) Separate placental masses in monochorionic pregnancies due to bipartite placenta; (3) False negative and false positive λ sign can arise for various reasons, and in partial monochorionic / dichorionic placentas both T and λ sign may co-exist; (4) Intrauterine synechia appearing as a thick and echogenic intrauterine septum may lead to erroneous diagnosis of dichorionic twins; (5) Errors in ascertaining amnionicity b y the visualization of thin inter-twin amniotic membranes and the number of yolk sacs.

Source: American Journal of Obstetrics and Gynecology - February 17, 2018 Category: OBGYN Authors: Jing Lu, Yvonne Kwun Yue Cheng, Yuen Ha Ting, Kwok Ming Law, Tak Yeung Leung Tags: Expert Review Source Type: research