Ultrasonic prediction of growth discordancy by intertwin difference in abdominal circumference

Abstract

Intertwin abdominal circumference (AC) and femur length (FL) differences were studied in 24 growth‐discordant (⩾15% birth weight difference) and in 32‐growth concordant twin pairs delivered within 2 weeks of the last ultrasonic examination. Both groups were of similar gestational age but differed significantly in the mean twin birth weight and intertwin AC difference (P = 0.01 and P = 0.00009, respectively). A cutoff value (⩾18 mm) for AC difference was found to discriminate significantly (P < 0.0009) between concordant and discordant pairs with sensitivity, specificity, positive predictive value and negative predictive value of 66.7%, 78%, 69.5% and 75.7%, respectively. These data may suggest that an intertwin difference of 18 mm or more in AC effectively screens for the diagnosis of 15% or more birth weight difference in twin pregnancies.