The wavering midline: A diagnostic sign of fetal hydrocephalus

The significance of midline wavering in the central nervous system as a diagnostic sign in hydrocephalus was evaluated prospectively in 27 hydrocephalic fetuses. No normal fetuses in a control group exhibited a wavering midline at three different times in pregnancy. Wavering along the entire length of the midline was seen in all 27 affected infants with hydrocephalus diagnosed from 12 to 42 weeks' gestation, prior to determination of an abnormal lateral ventricular width: hemispheric width ratio in one of 23 cases for which data were available and prior to an increased biparietal diameter in 25 (48%). One fetus, not included in the series, showed wavering of the midline echo and had an abnormal lateral ventricular width: hemispheric width ratio. The neonate was later shown to have trisomy 21 (47,XY,+21) and is suspected to have had a transient ventriculomegaly. Wavering along the complete length of the midline echo appears to be a constant finding in hydrocephalus in the fetus.