Intramuscular Versus Intravenous Anti-D for Preventing Rhesus Alloimmunization during Pregnancy

Summary

A Cochrane review [Abstract] 1 included 2 studies with a total of 447 RhD negative women. The studies compared intravenous (IV) and intramuscular (IM) administration of anti-D prophylaxis. In both studies the women received a 1500 IU (300 microgram) dose of Rhophylac during week 28 of gestation. There was no incidence of RhD alloimmunization in either of the studies, as the sample size was insufficient. One of the studies found that the mean anti-D IgG concentrations after IV and IM administration differed up to seven days (36.1 (2.6) ng/mL IV; 19.8 (8.7) ng/mL IM on day seven). However, from 2 to 3 weeks post-administration, the concentrations were similar for both routes of administration. None of the women involved in the studies developed antibodies against the RhD antigen.