<prompt> Most common cause of fetal ventriculomegaly is?Arnold Chiari malformation -IArnold Chiari malformation -IIAqueductal stenosisDandy Walker malformation  <response>: Ans. is c i.e., Aqueductal stenosis Hydrocephalus is characterized by an increased CSF volume with progressive ventricular dilatation ventriculomegaly. o Obstructive or noncommunicating hydrocephalusventriculomegaly develops most commonly in children because of an abnormality of the aqueduct or a lesion in the 4 ventricle. o Obstruction of the aqueduct is the single most common cause of fetal and neonatal hydrocephalus ventriculomegaly. o Nonobstructive or communicating hydrocephalus most commonly follows a subarachnoid hemorrhage, which is usually a result of intraventricular hemorrhage in a premature infant. 