Fetal ventriculomegaly and herpes encephalitis following primary maternal herpes simplex infection

Uteroplacental transmission of a primary herpes simplex virus (HSV) infection in pregnancy has been reported; however, HSV ventriculomegaly of the neonate has not been well documented in utero. We present a case of a 19-year-old woman who developed a primary HSV outbreak at 17 weeks of gestation and was treated with acyclovir. A congenital malformation scan at 18 weeks of gestation demonstrated no fetal abnormalities; however, an ultrasound at 33 weeks showed a new finding of ventriculomegaly. Additionally, hydrocephalus was confirmed with magnetic resonance imaging. New-onset ventriculomegaly in the setting of primary HSV infection in pregnancy should be considered as an in utero diagnostic indicator of antenatal herpes simplex infection and herpes encephalitis.