How accurate is antenatal sonographic identification of discordant birthweight in twins?

Abstract

The association between discordant birth weight in twins and poor perinatal outcome is well recognised. Antenatal identification of discordant fetal growth in twins using ultrasound has been previously reported. In this study we have assessed the accuracy of interpair percentage estimated fetal weight difference determination (interpair EFW%) in identifying an interpair percentage birth weight difference (interpair BW%) of ⩾20% and ⩾25% in 85 twin pregnancies. The maximum sensitivity, specificity, positive and negative predictive values we noted were 54.5, 98.5, 75 and 94.4%, respectively. These results suggest that interpair EFW% results should be interpreted with caution when used in the antenatal assessment of birth weight in twin pregnancies.