Prevalence of maternal red cell alloimmunisation: a population study from Queensland, Australia

The aim of this study was to determine the current prevalence of red cell antigen alloimmunisation in Australia. Blood group (ABO and RhD) and red cell antibody screen results of pregnant women who presented at public hospitals in Queensland between the period of January 2011 and June 2013 were evaluated retrospectively. Antibody prevalence in pregnancy was compared to other published studies. A total of 482 positive antibody screens from 66,354 samples (0.73%) were identified. The prevalence of antibodies was: anti-E 27.6%; anti-D 10.4%; anti-Kell 9.5%; anti-c 8.7%; anti-Duffy 3.1%, including Fy and Fy; anti-MNS 7.9%, including M, N, S and s; anti-Lewis 6%, including Le and Le; and multiple antibodies (16%, including anti-D). Compared to other studies, including one from Australia in 1977, the anti-D alloimmunisation rate had dropped significantly, with little change in anti-c and some increase in anti-E and anti-Kell cases. Continued vigilance is required to ensure eligible RhD negative women receive prophylaxis according to the current RhD immunoprophylaxis guidelines, especially those who have a fetomaternal haemorrhage (FMH). RhD positive women that are at risk of developing an antibody during pregnancy should have their pregnancy monitored according to published guidelines. Once antibodies are identified, consideration should be given to paternal antigen status in an attempt to identify the pregnancy that will be at risk of alloimmunisation.