Journal of Ultrasound in Medicine, Vol 5, Issue 3 141-144, Copyright © 1986 by American Institute of Ultrasound in Medicine
Femur length/abdominal circumference ratio. Poor predictor of macrosomic fetuses in diabetic mothers
C. B. Benson, P. M. Doubilet, D. H. Saltzman, M. F. Greene and T. B. Jones
Antenatal diagnosis of fetal macrosomia can affect the management of
diabetic mothers. Because the sonographically determined femur
length/abdominal circumference (FL/AC) ratio has been shown to differ in
macrosomic and non-macrosomic fetuses (in a population containing few
diabetics), its value in establishing the diagnosis of macrosomia was
examined. The results indicate that the FL/AC ratio differs in
non-macrosomic (20.4 +/- 1.6) and macrosomic (19.5 +/- 1.4) fetuses of
diabetic mothers, but there is considerable overlap. For no cutoff value is
there a high sensitivity and high specificity. The positive predictive
value is 36-43 per cent (depending on the cutoff), only slightly greater
than the prevalence (26 per cent in the study population). The authors
conclude that the FL/AC ratio is not useful in predicting macrosomia among
diabetic mothers.
