Electron microscopic identification of parvovirus virions in erythroid-line cells in fatal hydrops fetalis.

Intrauterine infection with parvovirus B19 may lead to fatal hydrops fetalis. Intranuclear particles, consistent with parvovirus virions, within erythroid cells were readily identified on transmission electron microscopy of formalin-preserved material obtained at necropsy from a neonate and two fetuses in whom clinical and light microscopic criteria for parvovirus B19 infection were met. No such particles were seen in similar material from a neonate and two fetuses with erythroblastosis fetalis due to alpha-thalassemia, maternofetal Rh incompatibility, and an erythrocyte membrane protein defect. When other means of investigation are impracticable transmission electron microscopy is widely available and easily performed and may be of value in establishing a diagnosis of parvovirus B19 infection.