First-trimester fetal neurosonography: technique and diagnostic potential.

Most of the brain abnormalities are present in fact also at first trimester but only a few of these are detected at such early stage. According to the current recommendations for the first trimester ultrasound, the fetal head structures that should be visualized are limited to the cranial bones, the midline falx and the choroid-plexus-filled ventricles. Using this basic approach almost all cases of acrania, alobar holoprosencephaly and cephalocele are usually detected, however the majority of the other abnormalities of the fetal central nervous system remain undiagnosed until midtrimester. Such anomalies are potentially detectable if the sonographic study is extended to additional anatomic details which are not currently included in the existing guidelines. The aim of this review article is to describe how to assess the normal fetal brain at first trimester expert multiplanar neurosonography and to demonstrate the early sonographic findings which characterize some major fetal brain abnormalities. This article is protected by copyright. All rights reserved.