Toxoplasmosis and parvovirus B19

infection of the fetus with Toxoplasma gondii may result in chorioretinitis, hydrocephalus, or, rarely, death. Maternal ante natal screening programs designed to diagnose and treat fetal infection are currently impractical because of the low rate of seroconversion during pregnancy, the low positive predictive value of serologic testing, and the necessity for invasive testing to determine appropriate antibiotic regimens. Similarly, maternal parvovirus B19 infection may cause fetal infection, hydrops, and death, but screening programs cannot be recommended. Ln the presence of hydrops, fetal transfusion may be life-saving, but hydrops may resolve without therapy. There are no definitive guidelines for determining which fetuses require transfusion.