Prenatal diagnosis of fetal corpus callosum agenesis by ultrasonography and magnetic resonance imaging.

Corpus callosum agenesis (CCA) was evaluated by ultrasound examination and magnetic resonance imaging (MRI) in 14 cases. Ultrasonography was able to suspect CCA by indirect signs but a definitive diagnosis of CCA was achieved in only four cases. MRI was able to diagnose complete CCA in 13 cases and showed absence of the posterior portion of the corpus callosum in one case. Additional neurological abnormalities including heterotopia, gyration anomaly, asymmetry of the cerebral hemispheres, and Dandy-Walker variant were documented in five cases, as well as an ocular anomaly which was present in one case, by MRI examination. Prenatal counselling for fetal agenesis of the corpus callosum is difficult as the prognosis is uncertain. The association with other cerebral abnormalities increases the likelihood of a poor outcome and ultrasonographic assessment of the fetal brain is limited. We found MRI to be a safe and useful additional procedure to complement ultrasonographic diagnosis or suspicion of CCA.