Four-dimensional sonographic assessment of inter-twin contact late in the first trimester

ObjectiveTo evaluate the total number of inter-twin contacts between monochorionic diamniotic (MD) and dichorionic diamniotic (DD) twins using four-dimensional (4D) sonography late in the first trimester of pregnancy.MethodSix MD and 8 DD pregnancies were studied for 30 minutes with 4D sonography at 10–11 and 12–13 weeks of gestation. A total of 10 types of inter-twin contact was evaluated.ResultsThere was a significant difference in the total number of all contacts between MD and DD twins at the 10–11 weeks of gestation (P < 0.05). There was also a significant difference in the total number of contacts between 10–11 and 12–13 weeks of gestation in DD twins (P < 0.05).ConclusionFour-dimensional sonography provides a means of evaluating inter-twin contact in the first trimester of pregnancy and could be an accurate and reliable tool in studies of inter-twin behavior.