Female, 28 years old, 32 weeks gestational age, with fetal brain abnormality on ultrasound. The lateral ventricles are markedly dilated. As a result, the cerebral cortex is severely thinned and somewhat dysmorphic. The septum pellucidum is not visualized and may have degenerated. The third ventricle is mildly dilated and the fourth ventricle is within normal limits. The cerebral aqueduct is not visualized.The interhemispheric falx is normally formed. The thalami are not fused. The corpus callosum is probably present but it is markedly thinned secondary to ventricular enlargement. The cerebellum appears mildly small for gestational age. No specific parenchymal signal abnormality is seen. No acute intracranial hemorrhage or any other abnormal extra-axial collections are suspected.
Marked lateral ventriculomegaly is seen which may be secondary to aqueductal stenosis as the cerebral aqueduct is not visualized. As a result, the cerebral cortex is markedly thinned and somewhat dysmorphic. However, there are no findings to suggest holoprosencephaly.