Height and Depth of the Three Levels of the Face in Second-Trimester Euploid Fetuses.

OBJECTIVE

To determine sonographic dimensions of the fetal upper, middle and lower facial profile levels in normal pregnancy at the second trimester scan (20-22 weeks).

METHODS

This was a prospective, cross-sectional study of 400 normal healthy fetuses at 20-22 weeks of gestation. The sagittal plane of the fetal facial profile was evaluated using transabdominal ultrasound. The three levels of the face were defined as it follows: a vertical line was drawn from the anterior edge of the sphenoid bone and then four parallel lines were drawn parallel to the long axis of the maxilla passing through the inflection point of the frontal bone, the nasion, the superior border of the maxilla and the gnathion.

RESULTS

The study population consisted of 400 low-risk pregnancies at 20-22 weeks gestation. We provided normative data in centiles of height and depth of upper, middle and lower levels of the fetal profile.

CONCLUSIONS

We provide normative data of the three levels (upper, middle and lower) of the fetal facial profile between 20-22 weeks. Our data offer a potential tool for the prenatal diagnosis of craniofacial anomalies and a comparative study with trisomy 21 fetuses currently underway.