To explore the clinical value of five axial planes of the fetal brain for detecting central nervous system (CNS) malformations.

All pregnant women who visited our center for a Level Ⅲ ultrasound scan were examined using five axial planes (the transcalvarial and trans-genu-and-splenium planes added to three traditional routine screening planes) to screen CNS malformations between January 2018 and December 2019. The types of CNS malformations detected using the five axial planes were analyzed and compared with those detected using the traditional routine screening planes.

During the research period, 2394 pregrant women underwent an evaluation of the fetal brain in the five preselected planes. In this cohort, 227 (9.5%) fetuses presented with 400 cerebral malformations. A total of 282 cerebral malformations in 115 (50.7%) fetuses were diagnosed using the three traditional planes. The other two planes provided additional diagnostic information in the remaining 112 (49.3%) fetuses with 118 cerebral malformations. Among them, 27 (11.9%) fetuses had abnormal manifestations only in the newly added planes, including agenesis of the corpus callosum (ACC), heterotopia, brain hemorrhage, schizencephaly, choroid plexus cyst, porencephaly, and arachnoid cyst. Of the 64 cases with abnormal development of cortical sulci, 45 showed abnormal parieto-occipital fissure in the transcalvarial plane. Seven of the nine cases with leukomalacia involving the centrum semiovale showed typical ultrasound findings in the transcalvarial plane. Of the 60 cases with ACC, 12 were diagnosed in the trans-genu-and-splenium plane, and this plane was also used to exclude the diagnosis of ACC in 35 cases with isolated abnormal septum pellucidum/cavum septum pellucidum.

The detection rate of fetal CNS abnormalities could be improved by using five axial planes. It is recommended that these planes be added for routine CNS malformation screening.