Neurosonography of Different Fetal Brain Structures during Second and Third Trimesters of Pregnancy

Background: Fetal brain anomalies are very common among pregnant women. Lateral ventricles, cavum septum pellucidum (CSP), cerebellum and corpus callosum (CC) are the main brain structures seen during fetal anomaly scan. Quantitative measurement of intracranial structures is mandatory for fetal CNS evaluation.Aim: To produce customized reference charts for different brain structures.Methods: Neurosonography is done at different gestational ages between 16-36 weeks' gestation in low risk mothers coming for routine anomaly scan. Measurement of anterior and posterior Frontal horns (FH), center to frontal horn diameter (CFHD), cerebellum, cisterna magna, CSP and CC.Results: A total of 110 women evaluated between 16-36 weeks' gestation. Reference tables including mean, 50th percentiles, upper and lower limits are all produced for intracranial structures at different gestations. The range of the upside AHW was 1.6 to 6.5mm, and the range of the downside AHW was 1.6 to 6.7mm. The largest upside PHW was 8.5mm at 17 weeks, and the largest downside PHW was 9.8mm at 17 weeks. The CSP was identified in 107 of 110 cases (97.2% of cases). The maternal Mean BMI was 33.15kg/m2 in cases of visualized CSP and 36.43kg/m2 in cases of non-visualized CSP (P value 0.4). The CC was identified in 105 of 110 cases from 16 to 36 weeks’ gestation (95.5% of cases). The maternal Mean BMI was 32.97kg/m2 in cases of visualized CC and 40.35kg/m2 in cases of non-visualized CC (P value 0.028).Conclusion: We produced localized customized reference charts for different brain structures to allow adequate quantitative assessment of fetal brain structures.