In the brain of a healthy fetus, the lateral ventricles of the brain are less than 10 mm wide. In the case of a fetus with ventriculomegaly, the lateral ventricles are between 10 mm and 15 mm wide; if they are even larger, the case is considered severe.

In most cases, ventriculomegaly is an isolated condition, so it is not linked to other health problems. However, a small portion of infants afflicted with ventriculomegaly have other health conditions, as well.

Severe cases of ventriculomegaly may result from hydrocephalus (water on the brain), in which CSF builds up and puts pressure on the brain.

• Impaired absorption of CSF (so the amount of CSF builds up and causes hydrocephalus)
• Improper brain development
• Destroyed brain tissue All three of these factors can increase the size of the ventricles in the brain.

Ventriculomegaly is detectable via fetal ultrasound by the second trimester. If your doctor suspects that your baby may have ventriculomegaly, an MRI of the fetal brain may also be recommended.

After birth: Diagnostic testing can identify ventriculomegaly at birth, as well. During the examination, the physician obtains a complete prenatal and birth history of the child. If there is a family history of ventriculomegaly, the physician can conduct a chromosomal analysis, either before or after birth, to test for those chromosome problems that cause ventriculomegaly.