This occurs in around 1% of pregnancies.
When this measurement is between 10 and 15 mm, the ventriculomegaly may be described as mild to moderate.
When the measurement is greater than 15 mm, the ventriculomegaly may be classified as more severe.
Enlargement of the ventricles may occur for a number of reasons, such as loss of brain volume (perhaps due to infection or infarction), or impaired outflow or absorption of cerebrospinal fluid from the ventricles. Often, however, there is no identifiable cause.
In many cases of mild ventriculomegaly, however, there is resolution of ventriculomegaly during the pregnancy.
To determine whether ventriculomegaly is associated with ongoing intracranial hypertension, physicians often rely on corroborative imaging features such as altered periependymal signal, distortion of ventricular shape, subarachnoid space flattening, and an increase in ventricular size over time.