Sonographic neuroembryology of the central nervous system

In the last decade, strong emphasis has been placed on the structural evaluation of the fetus. Central nervous system anomalies are among the most common malformations affecting the developing fetus. As ultrasound equipment has improved, our demand for more resolute pictures has increased. The high-frequency, transvaginal ultrasound probe allows us to access the fetal fontanel and produce high-resolution fetal brain images. When such transducer probes are aligned with the fetal anterior fontanel (much like neonatal brain scans), clear and clinically useful images in the sagittal and coronal planes are generated. In this article, we review the technique of transvaginal transfontanel scanning, discuss pertinent neuroembryology, and apply this information to the sonographic diagnosis of neural tube defects.