Fetal Advanced Neurosonography in the First Trimester of Pregnancy.

Introduction: Some of the central nervous system malformations (CNSs) can be detected or suspected during the first trimester.

Methods: Prospective observational study including singleton pregnancies, CRL between 60 and 82 mm and normal basic ultrasound examination. In the axial plane, we examined: lateral ventricles (LV), choroid plexus of LV (PCVL), PCVL/VL ratio, insula, cerebellum, distance from Sylvian aqueduct to occipital bone, IV ventricle (IVV), and cisterna magna (CM) and in the sagittal plane, we assessed: 4 lines-3 spaces, brain stem (BS), fourth ventricle, IVV choroid plexus (PC), CM, distance from BS to occipital bone (BSOB) and BS/BSOB ratio.

Results: Ninety-two fetuses were included. The extended examination was successfully performed in 86 (93.5%) cases. The insula, LV and CPLV (axial planes) as well as all structures in the sagittal planes were assessed at 100%. The IVV, PC and CM (axial planes) were visualized at 90 (97.8%) fetuses. In 89 (96.7%) fetuses, the cerebellum was successfully evaluated, while in 88 (95.7%) cases, the tectum, aqueduct of Sylvius, and Ac-Oc distance were measured. Good intra- and interobserver concordance was observed for all parameters, as confirmed by Bland-Altman analyses. Advanced ultrasound increased the total examination time by 3 min compared to basic examination.

Conclusions: Advanced first-trimester CNS assessment, including the incorporation of early markers to predict CNS abnormalities, is feasible with good intra- and interobserver agreement and minimal additional ultrasound scanning time.