Outcome prediction in monochorionic diamniotic twin pregnancies with moderately discordant amniotic fluid

Objective The aim of this study was to identify predictors of twin‐to‐twin transfusion syndrome (TTTS) and selective intrauterine growth restriction (sIUGR) in monochorionic diamniotic (MCDA) twin pregnancies with moderate amniotic fluid discordance (mAFD). Methods Monochorionic twins with mAFD (n = 45; gestational age, 15–29 weeks) were assessed for extent of fluid discordance, fetal growth discordance and fetal cardiac dysfunction, and were followed longitudinally. A prediction algorithm was constructed for TTTS and sIUGR and validated in an unrelated cohort (n = 52). Results Cardiac dysfunction could not predict TTTS or sIUGR. Twins below 20 weeks of gestation with a fluid discordance of ≥ 3.1 cm had a risk of TTTS of 85.7%. Sensitivity for TTTS was nevertheless only 55%. An intertwin weight discordance of ≥ 25% had 63% sensitivity and 76% specificity for sIUGR without TTTS. Conclusion The outcome of MCDA twins with mAFD remains unpredictable, yet high‐risk and low‐risk subgroups for TTTS can be identified based on severity of fluid discordance and gestational age. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.