Ultrasonic variables in the diagnosis of intrauterine growth retardation

Ultrasonic biparietal diameter (BPD), femur length, abdominal circumference, femur length/abdominal circumference ratio, estimated fetal weight, ponderal index, estimated fetal length were measured within 72 h of delivery of 30 small-for-date (SFD) and 174 non-SFD newborns. Evaluation of each ultrasound variable in the antenatal diagnosis of SFD fetus was assessed. Abdominal circumference and estimated fetal weight were the best predictors in confirming SFD in 73.3 and 76.6 per cent respectively, followed by BPD (63.3%). Other variables (femur length, femur length/abdominal circumference ratio, estimated fetal length and ponderal index) were less accurate in diagnosis of SFD babies. For all variables studied negative predictive value was high (almost 90% or above). However, positive predictive value for abdominal circumference and estimated fetal weight were satisfactory. This study demonstrates the usefulness of abdominal circumference and estimated fetal weight in recognising SFD. It also shows that various growth variables could be used to rule out the diagnosis of IUGR with reasonable accuracy (negative predictive value greater than or equal to 90).