Aneuploidy and Isolated Mild Ventriculomegaly

<i>Background:</i> Does the prenatal ascertainment of isolated mild ventriculomegaly increase the a priori risk for aneuploidy when isolated or not associated with advanced maternal age? Does isolated mild ventriculomegaly increase the risk for pediatric developmental delay? <i>Methods:</i> The Wayne State University (WSU) Reproductive Genetics abnormal case data base and the Madigan Army Medical Center (MAMC) experience were reviewed to compare the rates of aneuploidy for cases with fetal ventriculomegaly. Cases were classified by maternal age and associated sonographic markers of aneuploidy. Aneuploidy rates were compared between the isolated ventriculomegaly, ventriculomegaly with advanced maternal age (AMA), and ventriculomegaly associated with multiple anomalies. Rates of aneuploidy were compared to identify association. <i>Results:</i> A total of 118 cases with ventriculomegaly were identified for comparison. Ninety-four cases were identified in the WSU cohort; 46 demonstrated isolated ventriculomegaly alone, and aneuploidy was present in 3/25 (12%) with invasive fetal testing, 0/24 (0%) cases in the MAMC cohort demonstrated aneuploidy. Isolated mild ventriculomegaly cases at MAMC were identified for further tests. <i>Discussion:</i> Although the two study populations vary in age and risk distributions, the attributable risk for isolated mild ventriculomegaly poses a counseling conundrum due to the neurodevelopmental implication of this minor dysmorphism more so than its association with aneuploidy.