Efficacy of intrauterine volume, fetal abdominal area and biparietal diameter measurements with ultrasound in screening for small-for-dates babies

Summary. The efficacy of total intrauterine, intra-amniotic and placental volume measurements with ultrasound in screening for low birthweight (10th and 3rd centile) was compared prospectively with fetal biparietal diameter and abdominal area measurements at 32 and 36 weeks gestation in an unselected population of 362 women. In all of them the gestation was dated by ultrasound in the first half of pregnancy. Reference values were from a separate normal population studied previously. Total intrauterine volume showed the highest sensitivity in predicting babies weighing 10th centile (58% at 32 weeks and 62% at 36 weeks) and those weighing 3rd centile (78% at 32 weeks and 83% at 36 weeks). A higher number of false-positive tests resulted in a lower predictive value of a positive test (mean 34% for babies weighing 10th centile) than that found for abdominal area (mean 54%). Abdominal measurements selected a smaller'at risk'group. Biparietal diameter, intra-amniotic and placental volume measurements had inferior predictive capability than total intrauterine volume and abdominal area. For screening purposes abdominal area measurements are presently more suitable than intrauterine volume. The higher sensitivity of intrauterine volume, particularly in early third trimester, is an advantage that requires further investigation with reference to intrauterine growth retardation.