How to diagnose rubella during pregnancy.

Diagnosis of rubella during pregnancy is a challenge in a woman who is seronegative at the initial prenatal visit or in whom there has been no prior testing for rubella immunity. Detection of hemagglutination-inhibiting antibody is usually the best test. Diagnosis depends on a fourfold rise in antibody titer between paired acute and convalescent sera. In certain circumstances, it is necessary to ascertain complement-fixing antibody, fluorescent antibody or rubella-specific IgM.