Comparison of radioimmunoassay and the gel filtration technique for routine diagnosis of rubella during pregnancy.

Radioimmunoassay (RIA) for rubella-specific IgM antibodies was compared with haemagglutination-inhibition (HI) in conjunction with gel filtration for the diagnosis of rubella infection in pregnant women during a 1-year period. In total 476 women were investigated of whom 221 were tested for rubella IgM. Both techniques gave positive results with 64 sera, and RIA alone with one additional serum. Difficulties associated with the removal of non-specific HI activity were encountered with four sera all of which were negative by RIA. RIA was found to have practical advantages over the gel filtration method but is at present technically more difficult to perform.