Prenatal diagnosis of agenesis of the corpus callosum.

The prenatal sonographic findings in seven cases of agenesis of the corpus callosum (AGCC) are reported. Findings that suggest AGCC on standard transverse views of the fetal cranium are emphasized. All seven cases demonstrated ventricular abnormalities including four fetuses (57%) who demonstrated laterally displaced lateral ventricles and/or disproportionate enlargement of the occipital horns. Two additional fetuses demonstrated a large midline fluid collection, representing a dilated third ventricle. The remaining case demonstrated atypical findings of a septated periventricular cystic mass. Following birth, additional malformations were found in 5 of the 7 fetuses (71%), including one fetus with trisomy 8. We conclude that AGCC can be suggested on the basis of prenatal sonographic findings and that awareness of typical findings should permit more frequent detection of this anomaly in utero. Due to the frequency of concurrent anomalies, identification of AGCC should initiate a careful search for additional malformations.