[False rubella diagnosis in pregnancy by IgM enzyme immunoassay].

On the basis of a case report of a false-positive rubella diagnosis in early pregnancy the interpretation of positive IgM is discussed. A primigravida at 14 weeks of gestation showed rubella-specific IgM in an enzyme immunoassay. This result could not be confirmed by an alternative method (hemagglutination-inhibiting test after separating the serum by density gradients into different immunoglobulin classes and removal of the IgG with protein A). The immunological status corresponded with a past rubella infection or with the status after vaccination (IgG-positive). It is therefore recommended to use an additional method in the presence of IgM, especially if an interruption of the pregnancy has to be considered. In the course of the examination a recent cytomegalovirus infection could be detected.