Journal of Ultrasound in Medicine, Vol 16, Issue 6 401-405, Copyright © 1997 by American Institute of Ultrasound in Medicine
Growth of the fetal forehead and normative dimensions developed by three-dimensional ultrasonographic technology
E. Sivan, L. Chan, B. Uerpairojkit, G. P. Chu and E. A. Reece
Department of Obstetrics, Gynecology, and Reproductive Sciences, Temple University School of Medicine, Philadelphia, PA 19140, USA.
Sonographic imaging of the fetal face is important since a number of
chromosomal aberrations are associated with facial malformations. In the
past, imaging of the fetal forehead and diagnosis of frontal bossing had
been based on subjective evaluation using two-dimensional ultrasonography.
The purpose of this study was to evaluate quantitatively the fetal forehead
using three-dimensional technology to generate normative data throughout
gestation. This should allow the objective diagnosis of abnormal growth of
the fetal forehead, such as frontal bossing. We also report a case of a
fetus with frontal bossing in whom the generated nomogram was applied. A
cross-sectional study was performed in 130 normal healthy singleton
pregnancies between 16 and 38 weeks' gestation. Using three-dimensional
ultrasonography, a line connecting the apex of the philtrum and the nasion
was drawn across the anterior forehead, which delineated the area of the
forehead for analysis. The forehead length, forehead height, and forehead
area under the curve were measured and the forehead index was calculated. A
second order polynomial growth function was noted throughout gestation for
the forehead length (r = 0.93), forehead height (r = 0.97), and forehead
area (r = 0.97). The fetal forehead index remained relatively constant
throughout gestation. The results of this study provide normative data of
fetal forehead length, width, and area using three-dimensional
ultrasonographic technology. Normative dimensions of the fetal forehead
developed and presented herein are expected to serve as a basis for the
objective assessment of presumed fetal facial abnormalities and may
facilitate the detection of the associated syndromes. This is demonstrated
in our case report of an achondroplastic fetus in whom all forehead
dimensions were above the 95th percentile.
