Journal of Ultrasound in Medicine, Vol 3, Issue 4 163-168, Copyright © 1984 by American Institute of Ultrasound in Medicine
Fetal weight estimation from lengths and volumes found by three-dimensional ultrasonic measurements
J. F. Brinkley, W. D. McCallum, S. K. Muramatsu and D. Y. Liu
A custom-built computer system combined with a commercial real-time
ultrasonic scanner was used to predict fetal weight. A special
three-dimensional (3D) locating system provided 3D coordinates of fetal
surface points imaged on multiple ultrasound scans. The 3D coordinates were
used to develop length and volume variables that are not available with
commercial instruments. Multiple regressions were used to compare these
lengths and volumes with more conventional diameters and circumferences for
their ability to predict fetal weight. Measurements were made on 41 live
fetuses within 48 hours prior to delivery (weight range 1,985-4,734 g, mean
weight 3,421 g). Combinations of 19 measured variables were analyzed
against birth weight and the natural log of birth weight. The correlation
between log birth weight and combinations including lengths from 3D
measurements was R = .93, SE = 73 g/kg. When volumes from 3D measurements
(which are much more difficult to obtain) were added, the correlation was R
= .94, SE = 69 g/kg. These results suggest that lengths from 3D
measurements have the potential to improve fetal weight prediction by 25-30
per cent over current methods, which have an approximate error of 100 g/kg.
The relative lack of improvement with volumes from 3D measurements is
probably the result of technical problems which may be overcome with
further research.
