Ultrasound prediction of intertwin birth weight discordance in monochorionic diamniotic twin pregnancies

Abstract

Objectives To estimate the accuracy of ultrasound to predict birth weight (BW) and BW discordance in monochorionic diamniotic (MCDA) twin pregnancies. Methods A prospective series of MCDA twin pregnancies was subjected to ultrasound fetal weight estimations (EFW) at 16, 20, and 26 weeks of gestation and within 2 weeks of birth. Intertwin weight discordance (ΔEFW and ΔBW) was calculated. The correlation between ΔEFW, ΔBW, EFW, and BW was assessed (Pearson) and least square regression analysis was performed. Positive and negative predictive values of ultrasound to detect severe ΔBW were calculated. Receiver‐operating characteristics (ROC) curves were constructed to predict ΔBW >25% at different time points of gestation. Results Sixty pregnancies were included. Median ΔBW was 9.98%. Ten(16,7%), 8(13,3%) and 5(8,3%) twin pairs had a ΔBW >20%, >25% and >30%, respectively. BW and EFW (r = 0.96; p < 0.001) as well as ΔBW and ΔEFW were well correlated with each other (r = 0.75; p < 0.001). Bland‐Altman analysis showed that ultrasound evaluation overestimated ΔBW if >20%. Negative predictive value of ultrasound for ΔBW >25% was 98%. The area under the curve (AUC) to predict a ΔBW >25% at 16, 20, and 26 weeks and <2 weeks before birth was 0.79, 0.87, 0.93, and 0.95, respectively. Conclusions Ultrasound estimations of BW and ΔBW are highly correlated with actual BW and ΔBW in MCDA twin pregnancies. Copyright © 2009 John Wiley & Sons, Ltd.