Two-Dimensional Ultrasound Evaluation of the Fetal Cerebral Aqueduct: Improving the Antenatal Diagnosis and Counseling of Aqueductal Stenosis.

OBJECTIVE

To describe a technique for the visualization and measurement of cerebral aqueduct diameter through a 2D sagittal median plane, and to report its aspect and measurement in fetuses with aqueductal stenosis (AS).

METHODS

This was a cross-sectional study of 207 morphologically normal fetuses in low-risk pregnancies between 20 and 36 weeks of gestation. The cerebral aqueduct was visualized transvaginally in a midsagittal plane, and measurements of its greatest diameter (ampulla) were taken independently by an expert and a nonexpert sonographer. In addition, the aqueduct morphology from 7 fetuses with AS and complete follow-up were compared to the reference range.

RESULTS

Aqueductal measurements were obtained in 206 of 207 normal fetuses. Aqueductal growth occurred linearly with gestational age. Our method demonstrated excellent interobserver reproducibility. Among the 7 fetuses with AS, the aqueductal lumen could not be identified in 6 and had a funneling aspect in 1.

DISCUSSION: Our study demonstrated that it is possible to visualize and measure the cerebral aqueduct directly through a 2D ultrasound median plane. In fetuses with severe ventriculomegaly, the morphology and width of this structure could represent a relevant tool in improving AS diagnosis, differentiating it from other causes of significant ventricular dilation that carry a different outcome.