Sonography of unilateral megalencephaly in the fetus and newborn infant.

A 27-year-old primigravida women was referred for ultrasound studies at 32 weeks' gestation because of the suspicion of fetal ventriculomegaly. Sonographic examination of the fetal brain found a marked shift of the midline, with enlarged left hemisphere and ipsilateral occipital horn, and abnormal convolutions. A 3500 gm male infant was delivered by cesarean section at 39 weeks' gestation because of worsening macrocrania after which the diagnosis of unilateral megalencephaly was confirmed by computed tomography.