Journal of Ultrasound in Medicine, Vol 5, Issue 12 707-710, Copyright © 1986 by American Institute of Ultrasound in Medicine
Intrapartum fetal weight estimation: a comparison of three formulae
S. Yarkoni, E. A. Reece, M. Wan, T. Holford, R. Romero and J. C. Hobbins
To determine the relative accuracy of fetal weight estimation using the
biparietal diameter (BPD), the abdominal circumference (AC), and the femur
length (FL) in three formulae (BPD/AC, FL/AC, and BPD/AC/FL), 63 patients
in labor were examined. All patients delivered within 24 hours of
ultrasound examination. A good correlation was found between the estimated
fetal weight and the actual birth weight, using the three formulae: BPD/AC
(r = 0.96); FL/AC (r = 0.95); and BPD/AC/FL (r = 0.96). The FL/AC formula
overestimated fetal weight (P less than 0.01), however, particularly in
fetuses weighing more than 2000 g. The mean percentage error with the
BPD/AC formula was 0.99 per cent, 3.82 per cent with the FL/AC, and 2.43
per cent with the BPD/AC/FL formula. This study showed that although all
three formulae were comparable, the best estimation of the birth weight was
obtained when either the BPD/AC or the BPD/AC/FL formulae were used.
Additionally, the results demonstrate that reliable estimates of fetal
weight can be made even at term or in laboring patients.
