Retrospective validation of 11–13 weeks’ gestation ultrasound characteristics as predictive tools for twin-twin transfusion syndrome and selective intrauterine growth restriction in monochorionic diamniotic twin pregnancies

BACKGROUND: Twin to twin transfusion syndrome (TTTS) is a serious syndrome that can affect twin pregnancies involving a single placenta, impacts some of twin gestations with monochorionic diamniotic (MCDA) placentas. We validated the ultrasound characteristics of 11–13 weeks’ gestation to predict TTTS and selective intrauterine growth restriction (sIUGR) in MCDA pregnancies. METHODS: We retrospectively included all of the MCDA twin pregnancies with ultrasound characteristics, including the crown-rump length (CRL), ductus venosus pulsatility index for veins (DV PIV), and nuchal translucency (NT) thickness, at 11–13 weeks’ gestation, followed by mean difference and discordance comparison. Receiver operating characteristic (ROC) curves were constructed for the comparison of values of these predictive markers for identification of MCDA pregnancies with high-risk of adverse outcomes. RESULTS: A total of 98 MCDA pregnancies were included in this study. Among the 98, 34 (34.7%) developed sIUGR, whereas 10 (10.2%) expressed TTTS. Significant differences in NT discordance were found among the normal, sIUGR, and TTTS groups; moreover, a significant difference was found between pregnancies with normal outcomes and sIUGR (P<0.001), normal and TTTS (P<0.001), and sIUGR and TTTS (P<0.001). Difference in NT was determined to be the best predictive marker for sIUGR [area under the curve (AUC) =0.769; 95% confidence interval (CI): 0.591 to 0.992], and NT discordance was considered the best predictive marker for TTTS (AUC =0.802; 95% CI: 0.485 to 0.936). CONCLUSIONS: Significant differences in NT discordance were found between the normal, sIUGR, and TTTS groups, while NT difference and NT discordance were identified as predictive markers for sIUGR and TTTS, respectively.