Prenatal diagnosis of unilateral megalencephaly by real-time ultrasonography.

Unilateral megalencephaly is a rare anomaly of neuronal cell migration. We recently diagnosed this condition in a fetus at 20 weeks' gestation with ultrasonography and magnetic resonance imaging. The pregnancy was terminated and postmortem magnetic resonance imaging and autopsy confirmed the diagnosis. To our knowledge this represents the first case to be prenatally diagnosed with certainty.