BIRTH-WEIGHT PREDICTION BY 3-DIMENSIONAL ULTRASONOGRAPHIC VOLUMES OF THE FETAL THIGH AND ABDOMEN

Our validation study examined a three-dimensional ultrasonographic pha ntom that contained irregularly shaped volume targets ranging from 0.5 to 76.1 milliliters. Four different examiners made blinded measuremen ts from volume datasets that were acquired by 4 and 7 MHz transducers. Birthweight predictions using abdominal and thigh volumes from 18 ter m fetuses also were compared with two-dimensional ultrasonographic met hods. In vitro volume measurements were accurate, precise, and repeata ble despite a small systematic overestimation with increasing object s ize. Mean systematic error and precision for birthweight predictions t hree-dimensional ultrasonography (-0.03% +/- 6.1%) were not significan tly different from those by two-dimensional ultrasonography (-0.60% +/ - 8.8%). Conventional prediction methods yielded three birthweights wi th greater than 15% error. By comparison, except for one infant whose birthweight indicated an 11% error, all predictions based on fetal vol ume parameters were within 10% of true values. Accurate birthweight pr edictions by fetal volume parameters appear to be technically feasible at term gestation although their practical clinical application requi res further investigation. Birthweight predictions in this manner may allow remote consultants to evaluate the fetus over wide-area computer networks despite the physical absence of the patient.