Anatomical subgroup analysis of the MERIDIAN cohort: failed commissuration

Objective: To assess the contribution of in utero magnetic resonance (iuMR) imaging in fetuses diagnosed with either agenesis of the corpus callosum or hypogenesis of the corpus callosum (grouped as failed commissuration) on antenatal ultrasonography (USS) from the MERIDIAN cohort. Methods: We report a sub-group analysis of fetuses with failed commissuration diagnosed on USS (with or without ventriculomegaly) from the MERIDIAN study who had iuMR imaging within 2 weeks of USS and outcome reference data were available. The diagnostic accuracy of USS and iuMR are reported as well as indicators of diagnostic confidence and effects on prognosis/clinical management. Results: 79 fetuses with failed commissuration are reported (55 with agenesis and 24 with hypogenesis as the USS diagnoses). The diagnostic accuracy for detecting ‘failed commissuration’ as a group label was 34.2% for USS and 94.9% for iuMR (difference = 60.7%, 95% confidence interval 47.6% to 73.9%, p