Journal of Ultrasound in Medicine, Vol 1, Issue 9 359-360, Copyright © 1982 by American Institute of Ultrasound in Medicine
An evaluation of two methods for measuring fetal head and body circumferences
F. P. Hadlock, W. R. Kent, J. L. Loyd, R. B. Harrist, R. L. Deter and S. K. Park
Department of Radiology, Baylor College of Medicine, Houston, Texas.
Head and abdominal circumference measurements of 166 fetuses (15-40 weeks)
were made by three different examiners using two measurement techniques. In
method 1 the actual circumferences were measured using an electronic
digitizer, while in method 2 the circumference measurements were estimated
using the formula for calculating the circumference for an ellipse.
Evaluation of the entire data set as a whole demonstrated no significant
mean errors (P > 0.05), and only a small degree of variability (2 SD = 6
per cent). Evaluation of the data for each examiner demonstrated no
significant differences (P > 0.05) in the observed variability, but
small statistically significant mean errors (1.7-4.1 per cent) were
observed. The latter finding is thought not to be a limitation of the
ellipse approximation technique, since similar findings have been observed
when experienced sonographers make actual circumference measurements on the
same fetus using the same equipment.
