Laboratory investigations in the assessment of rubella during pregnancy.

The relationship between rubella acquired in the first four months of pregnancy and subsequent congenital malformation makes it important that mothers who contract rubella during early pregnancy are diagnosed accurately. The recent development of techniques for both virus isolation' 2 and serological diagnosis has made it possible for the laboratory to assist clinicians in the assessment of such problems. At present a few public health and hospital laboratories undertake such investigations, but it seems likely that in future these facilities will become widely available. As rubella often presents atypically, a diagnosis on clinical grounds alone is prone to error. Moreover, infection by other viruses, such as certain enteroviruses, may produce an illness in which the clinical features closely resemble rubella. Inapparent infection has been reported in such closed population groups as military recruits and children in residential institutions, in whom the ratios of inapparent to apparent infection were 6: 1 and 1: 1 respectively3 ; however, the incidence of inapparent infection in more general communities has yet to be determined. Nevertheless, maternal inapparent infection may result in congenital malformation,17 and therefore women exposed to rubella during pregnancy should whenever possible be carefully assessed both clinically and virologically.