Routine obstetric ultrasound: effectiveness of cross-sectional screening for fetal growth retardation

Sonographic detection of fetal growth retardation was evaluated on a sample of 778 patients routinely scanned over a 16-month period. From the 29th week to term, the sensitivity of abdominal circumference measurement progressively increased from 41% to 88% (P less than 0.01). Higher rates were achieved by using the biparietal diameter but false-positive diagnoses were twice as frequent as with the abdominal measurements. When the limitations in precision of abdominal circumference were considered, the screening rate of this parameter increased about 16%. Moreover, 50% of the false-negative diagnoses were made on fetuses weighing between the fifth and 10th centiles at birth. These diagnostic indices for biparietal diameter and abdominal circumference evaluated on a retrospective series proved to be lower than those reported for the prospective selected series. However, the results yielded by routine ultrasound were better than those obtained with clinical or traditional biochemical methods. These findings underline the importance of sonography not only in serial control of high-risk pregnancies but also in cross-sectional screening programs.