[Viral infections and pregnancy: contribution of amniotic fluid and blood samples]

The main viral infections prenatally detected in fetuses are: cytomegalovirus, parvovirus B19, rubella virus and varicellazoster virus infections. Prenatal diagnosis is based on the direct detection of the virus by culture (CMV), of its antigens or of its genome, essentially by PCR. This direct detection can be done either on fetal blood or on amniotic fluid. Prenatal diagnosis can also be performed by detection of specific IgM in fetal blood (rubella). Non specific markers of viral infection can also help in diagnosis. At the present time, prenatal diagnosis is essentially based on the detection of the viral genome in amniotic fluid. In order to better appreciate the severity of fetal infections, some groups have tried to identify prognostic markers of these infections. The viral load as well as the level of specific IgM could play a role in certain infections (CMV).