The use of 3D ultrasound to investigate fetal bone development

Description/Abstract

Epidemiological studies suggest impaired fetal skeletal development has lifelong consequences for bone
health. To examine the feasibility of using 3-dimensional ultrasound (3DUS) to investigate influences on fetal
femur development, we obtained volume datasets of the uppermost fetal thigh at 19 and 34 weeks gestation in
517 women in a population-based survey of maternal nutrition. In addition to the standard measure of femur
length, we derived femoral cross-sectional areas and volume from the volume datasets.
Coefficients of variation for intra-operator variability in femur length were 0.6% at 19 weeks and 0.4% at 34
weeks; corresponding coefficients of variation for distal femoral cross-sectional area were 4.4% at 19 weeks and
3.2% at 34 weeks, showing greater measurement variability with a more complex technique. Intra-operator
variability for femur volume measurement triplets at 19 and 34 weeks was 3.4% and 1.7%, respectively.
The coefficients of variation of replicate measurements were compared with the between-subjects variation
as a measure of the biological variability between fetuses: at 19 weeks between-subjects variation was 7.2%
for femur length, 19.6% for distal cross-sectional area and 19.9% for femur volume. These results show a wide
range of variation between subjects, which is substantially greater than the intra-operator variability. This suggests
that the measurements of fetal femur size and volume are reproducible and can be used to examine biological
differences between subjects, and we found that femoral volume was greater in male fetuses at 19 weeks
gestation. Thus 3DUS presents a useful technique for assessing fetal skeletal development in cohort studies