VP25.01: The correlation between ultrasonographic diagnosis of fetal brain malformations and postmortem findings: a retrospective study

Abstract

Methods: This was a prospective study that included normal fetuses screened between 11 and 13 weeks of gestation. We measured the distance between the posterior limit of the mesencephalon to the occipital bone in the same axial view as the one required for the biparietal diameter (BPD) assessment, at this gestational age. The reference ranges were calculated using quantile regression, according to the Crown-rump length (CRL), BPD, and gestational age. Results: Data analysis included 428 ultrasound measurements. We observed a good, linear correlation between mesencephalon to occiput (MO) distance and CRL, BPD, or gestational age. It increased linearly with advancing gestation (log10MO =-0.1834 + 0.0092*CRL, r2 = 0.48, p < 0.0001) and was independent of maternal demographic characteristics and intracranial translucency. In our study, the 1st percentile of the normal MO distance varies from 1.31 mm at a CRL of 45 mm to 2.08 mm at a CRL of 84 mm. Conclusions: We described a simple measurement between the midbrain and the occipital bone, obtained in axial view. Integration into the routine screening in association with the "crash sign" and recognizing the lower extreme values could lead to an early diagnosis of open spina bifida.