P01.06: Combined imaging by specialized 2D/3D ultrasound and magnetic resonance in cases with abnormal cavum septi pellucidi (CSP) and corpus callosum (CC)

Abstract

Methods: This is a retrospective cross-sectional study of abnormal posterior fossa (PF) findings on second trimester ultrasound (US), and their relation to unfavourable pregnancy and early neonatal outcomes. All abnormal PF findings were initially included in the database search. Only cases presenting with increased pericerebellar fluid (IPCF) on US were included in this study. The US and MRI images were reviewed independently by 2 of the authors to categorise these findings into a diagnosis of Dandy-Walker continuum (DWC), mega-cisterna magna (MCM) or persistent Blake's pouch (PBP) as per the new classification scheme. If discrepancies were recorded, the cases underwent further joint review for a final diagnostic classification. Data on outcomes was collected from maternal and neonatal records: termination of pregnancy, stillbirths, neonatal deaths, chromosomal anomalies, presence of additional structural anomalies. Results: 46 cases presenting with IPCF were included in the study. They were classified as follows: 30 DWC, 7 MCM and 9 PBP. We present the perinatal outcomes as correlated with the reclassified categories and associated anomalies. Conclusions: Diagnosing anomalies of the PF presenting primarily as IPCF collections is challenging. Inconsistent classification schemes combined with difficulties in differentiating between these anomalies result in significant uncertainties as to the significance of the final diagnosis. Inevitably, prospective parents find themselves making difficult decisions based on scarce evidence. The revised classification scheme utilised in this study could provide sonologists with a consistent and reproducible diagnostic pathway that may assist in counselling.