The role of ultrasound examination in the first trimester and at 16 weeks' gestation to predict fetal complications in monochorionic diamniotic twin pregnancies

OBJECTIVE: The purpose of this study was to determine the value of ultrasound examination in the first trimester and at 16 weeks to predict fetal complications in monochorionic diamniotic (MCDA) twin pregnancies, defined as the occurrence of either twin-to-twin transfusion syndrome, severe discordant growth, or intrauterine death.

STUDY DESIGN: We identified risk factors to predict a complicated fetal outcome in the first trimester and at 16 weeks in a prospective cohort of 202 twin pregnancies recruited during the first trimester in 2 centers of the EuroTwin2Twin project.

RESULTS: Significant predictors in the first trimester were the difference in crown-rump length (odds ratio [OR], 11) and discordant amniotic fluid (OR, 10). At 16 weeks, significant predictors were the difference in abdominal circumference (OR, 29), discordant amniotic fluid (OR, 7), and discordant cord insertions (OR, 3). Risk assessment in the first trimester and at 16 weeks detected 29% and 48% of cases with a complicated fetal outcome, respectively, with a false-positive rate of 3% and 6%, respectively. Combined first-trimester and 16 week assessment identified 58% of fetal complications, with a false-positive rate of 8%.

CONCLUSION: Of the MCDA twin pregnancies classified as high risk on the combined first trimester and 16 weeks assessment (n = 41), 73% had a complicated fetal outcome with a survival rate of only 69%. In contrast, of the pregnancies classified as low risk (n = 154), 86% had an uneventful fetal outcome with a survival rate of 95%.