Why is the diameter of the fetal lateral ventricle measured during routine second trimester Ultrasound?
Measurement of the width of the lateral ventricle at the atrium is a standard second trimester fetal measurement used to detect hydrocephalus. Normally, the lateral ventricle diameter is <10 mm (usually 4 to 8 mm). A lateral ventricle measurement >10 mm is indicative of hydrocephalus.
A dangling choroid plexus surrounded by fluid in the lateral ventricle is a secondary sign of hydrocephalus. Possible etiologies for fetal hydrocephalus include cerebral acqueductal stenosis, neural tube defect with Chiari malformation, Dandy Walker malformation, hemorrhage, and infection.
