Fetal varicella - diagnosis, management, and outcome.

Fetal varicella syndrome (FVS) is due to transplacental infection by the Varicella zoster virus following maternal infection. The risks for the fetus and neonate depend on the timing. When varicella occurs around delivery, it often leads to disseminated neonatal varicella. When varicella occurs during pregnancy, transmission can occur, but is usually asymptomatic; some infants develop zoster postnatally and a few have FVS. Before 20 weeks' gestation, FVS can occur, with an incidence of about 1%. The lesions can affect the skin, limbs, central and autonomous nervous systems, eyes, cause calcifications, and growth retardation; mortality is high. Lesions typically follow one or several nerve territories, suggesting that damage results from in utero zoster following primary fetal infection. There has been little study of prenatal diagnosis of FVS. Serial ultrasound examination can detect various anomalies, magnetic resonance imaging can be of use to investigate for microphthamia and cerebral lesions, and amniocentesis can diagnose viral transmission. Prevention strategies include vaccination and post-exposure prophylaxis with immune globulin and/or antivirals. Perspectives for treating infected fetuses in utero require further research.