The dynamic fetal brain.

[hydrocephalus with stenosis of the aqueduct of sylvius]

To evaluate fetuses with normal intracranial anatomy in the second trimester that became abnormal in the third trimester .We sonographically examined 6 fetuses with a normal second -trimester head sonogram that presented later in pregnancy with an abnormal head sonogram .Four categories of intracranial pathology were depicted : obstructive hydrocephalus , intraventricular intracranial hemorrhage , non-intraventricular intracranial hemorrhage , and porencephaly .Despite a normal midtrimester intracranial examination , evaluation of the fetal intracranial contents should be undertaken in subsequent sonographic examinations , because significant pathology can develop spontaneously .