Background: Fetal ventriculomegaly is one of the more common fetal anomalies detected during prenatal screening.

Objectives: To assess the rate of genetic aberrations as the cause for ventriculomegaly in these fetuses.

Methods: A historic cohort study was conducted on 164 fetuses with sonographic diagnosis of ventriculomegaly. All cases were analyzed for karyotype and 41 cases were further analyzed by chromosomal microarray (CMA). The study group was subdivided by laterality, severity, and whether the ventriculomegaly was an isolated finding or not. Subgroups were compared and the study group was compared to a control group of 209 fetuses.

Results: Karyotype aberrations were more common among fetuses with ventriculomegaly (6.6%) compared to controls (0%, P < 0.001). CMA aberrations were more common in the non-isolated ventriculomegaly cases (24.1%) compared to controls (6.2%, P = 0.031). The rate of genetic aberrations was not associated with the degree of dilatation or laterality.

Conclusions: It is equivocal whether CMA testing should be conducted on every amniotic fluid sample taken from fetuses with isolated ventriculomegaly. However, if more anomalies are detected during an anatomical survey, CMA analysis should be conducted to decrease oversights of genetic diagnoses.