Accuracy of prenatal ultrasound in the diagnosis of corpus callosum anomalies.

Objectives: The main objective of this study was to evaluate the accuracy of prenatal ultrasound to diagnose corpus callosum alterations, compared to prenatal magnetic resonance imaging (MRI), postnatal image techniques (ultrasound and/or MRI), and post-mortem examination in terminated pregnancies. Methods: Retrospective review of 86 cases of prenatal ultrasound diagnosis of corpus callosum anomalies between January 2007 and December 2015 at a third level Maternal Fetal Medicine center. The study reviewed the findings of prenatal ultrasound and MRI, post-mortem examination in cases of termination of pregnancy (TOP) or stillbirths and postnatal ultrasound, and MRI in neonates. The anomalies of corpus callosum (CC) were classified as complete agenesis of the corpus callosum (ACC), partial ACC, or dysgenesis of CC. Results: Fifty-eight (67.4%) cases resulted in TOP, 26 (30.2%) cases opted to continue with the pregnancy and two (2.3%) cases were lost to follow up. Among the 26 cases that continued with the pregnancy, 24 (92.3%) were live births and two (7.7%) were stillborn. All cases in which a third trimester MRI was performed ( n  = 46) confirmed the prenatal ultrasound diagnosis of CC anomaly. In seven (15.2%) of them, the MRI found additional intracranial findings and in three cases (6.5%) the type of CC anomaly (complete, partial, or dysgenesis) was reclassified (Kappa index: 0.86, 95% CI: 0.71-1.00). CC anomalies were confirmed in 46 (95.8%) of the 48 cases in which a post-mortem examination was available, the type of anomaly being reclassified in three cases (6.3%) (Kappa index: 0.88, 95% CI: 0.75-1.00). Among the 10 cases in which a postnatal ultrasound was performed, the CC anomaly was confirmed in all and the type of anomaly was reclassified in 1 (10%) of them (Kappa index: 0.75, 95% CI: 0.32-1.00). Conclusion: Corpus callosum agenesis can be detected on the routine mid-trimester ultrasound scan. Prenatal ultrasound and MRI can accurately classify the type of CC abnormality. Moreover, third trimester MRI can detect additional intracranial anomalies in 15% of cases.