Prevalence of corpus callosum pathology in an unselected population. Should assessment of the corpus callosum be included in the routine 20 weeks scan?

ObjectivesTo determine the prevalence of abnormalities of the corpus callosum (AbnCC) in a non-selected population, to propose a systematic screening protocol for AbnCC in all populations through direct assessment, and to describe the follow-up and prognosis of all AbnCC cases diagnosed in our clinical setting.MethodsThis was a retrospective review of the prevalence of AbnCC over 11 years. We included a sagittal assessment of the corpus callosum (CC) in the second-trimester scan. AbnCC was classified into complete agenesis of CC (ACC) and dysgenesis of CC (DCC; including small, partial agenesis, thick and with lipoma).ResultsOf the 38,586 second-trimester scans performed during our screening, 43 cases of AbnCC were detected (prevalence of 0.8/1000). Of the AbnCC cases, 10 cases were identified as ACC (29.40%) and 24 as DCC (70.59%). Follow-up investigations showed that in the 43 cases with AbnCC, 76.5% had other associated ultrasound abnormalities, 26.5% had genetic abnormalities, 11.8% had other MRI abnormalities, and 25% of the children had neurodevelopmental delays (8.8% of the total), which were severe in only one case.ConclusionsAbnCC is found in approximately 0.8/1000 of cases in an unselected population. The findings suggest that systematic and direct assessment of the CC as part of screening ultrasound in the second trimester of gestation should be recommended as a routine practice. What's already known about this topic?Corpus callosum (CC) abnormalities often occur in association with other central nervous system (CNS) and extra-CNS anomalies, aneuploidies, or genetic syndromes, and carry a high risk of adverse neurodevelopmental outcomes.What does this study add?Direct assessment and visualization of the CC on screening ultrasound is possible, without using only indirect signs. The approximate prevalence of CC abnormalities in the unselected population is 0.8/1000.