Fetal trunk and head volume measured by three-dimensional ultrasound at 11 + 0 to 13 + 6 weeks of gestation in chromosomally normal pregnancies

Authors


Abstract

Objective

To establish the relationship between fetal trunk and head volume measured by three-dimensional (3D) ultrasound and gestational age at 11 + 0 to 13 + 6 weeks of gestation.

Methods

The fetal trunk and head volume were measured using 3D ultrasound in 417 chromosomally normal fetuses from singleton pregnancies at 11 + 0 to 13 + 6 (median, 12 + 0) weeks of gestation. Regression analysis was used to determine the significance of the association between fetal volume and gestational age. The Bland–Altman analysis was used to compare the measurement agreement and bias for a single examiner and between different examiners.

Results

The fetal trunk and head volume increased linearly with gestation from a mean of 5.8 mL at 11 + 0 weeks to 33.3 mL at 13 + 6 weeks and 1 SD was 4.4 mL. There was also a significant linear association between fetal volume and crown–rump length (CRL), from a mean of 5.1 mL at a CRL of 45 mm to 37.5 mL at a CRL of 84 mm and 1 SD was 2.7 mL. However, within this gestational range, a doubling in CRL, from a mean of 48 mm at 11 + 0 weeks to 79 mm at 13 + 6 weeks, was associated with a 5–6-fold increase in fetal volume. The mean difference in fetal volume between paired measurements by the same sonographer was −0.87 mL (95% limits of agreement, −2.31 to 4.05 mL) and the mean difference between paired measurements by two sonographers was −1.09 mL (−5.49 to 3.32 mL).

Conclusions

3D ultrasound can provide a reproducible measurement of the fetal trunk and head volume in early pregnancy. At between 11 + 0 and 13 + 6 weeks there is a 5–6-fold increase in fetal volume but only a doubling in CRL. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.

Ancillary