Ultrasound determination of fetal abdominal circumference: a comparison of measurement methods

The measurement of fetal abdominal circumference by the direct perimeter method using a digitizer was compared with calculation of this measurement using the fetal mean abdominal diameter in 235 cases. The directly measured abdominal circumference was found to be greater than the calculated value (p = 0.00014). The magnitude of the difference, however was only 1.3 +/- 2.2%, which is smaller than the average interobserver measurement error. Although statistically significant, the difference between these two measurement methods is not clinically significant, and these data and discussion show that either method is acceptable to determine fetal abdominal circumference.