Ventriculomegaly Mild fetal ventriculomegaly 2011-01-17T01:36:57Z UMLS:C4023628 A ventricular atrial diameter of more than 10 mm at 20-24 weeks of gestation has been accepted as defining ventriculomegaly because it represents at least 3 standard deviations above the mean (which is roughly 5 mm at 20-24 weeks of gestation). If the diameter is above 15 mm, the ventriculomegaly is considered to be severe. Amongst the most common causes of ventriculomegaly are impaired absorption of CSF, developmental cerebral defects, and destroyed brain tissue. Mild foetal ventriculomegaly A kind of ventriculomegaly occurring in the fetal period and usually diagnosed by prenatal ultrasound. Cerebral ventriculomegaly is defined by atrial measurements 10 mm or more. Mild ventriculomegaly (MVM) is defined as measurements between 10 and 15 mm. Measurements are obtained from an axial plane at the level of the thalamic nuclei just below the standard image to measure the BPD (PMID:16100637). HP:0010952 Fetal ultrasound soft marker Abnormal fetal central nervous system morphology