Placental and fetal pathology in intrauterine viral infections.

Intrauterine viral infections show a wide range of fetal involvement with variable fetal outcome. The histopathologic changes of the placenta during viral infection show a wide spectrum. The most active processes are proliferative with a variety of cells involved. Vascular changes, including inflammatory and obliterative lesions, are frequently found leading ultimately to fibrosis of the villous stroma. Abnormalities of villous maturation occur, especially in early onset infections, sometimes with edematous features. In cases of fetal injury, intrauterine death and nonimmunologic fetal hydrops may occur, viral infection must be suspected. In several cases placental examination using conventional and molecular techniques may explain the clinical findings.