This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
[{'content': 'Most common cause of fetal ventriculomegaly is ? \nSelect and explain. \nA. Arnold Chiari malformation–I, B. Arnold Chiari malformation–II, C. Aqueductal stenosis, D. Dandy Walker malformation', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Hydrocephalus is characterized by an increased CSF volume with progressive ventricular dilatation (ventriculomegaly).\nObstructive or noncommunicating hydrocephalus/ventriculomegaly develops most commonly in children because of an abnormality of the aqueduct or a lesion in the 4th ventricle.\nObstruction of the aqueduct is the single most common cause of fetal and neonatal hydrocephalus/ ventriculomegaly.\nNon obstructive or communicating hydrocephalus most commonly follows a subarachnoid hemorrhage, which is usually a result of intraventricular hemorrhage in a premature infant.', 'role': 'assistant'}]