Introduction: Introduction The Hy antigen is one of ten red cell antigens belonging to the Dombrock blood group system, with an antigen frequency of almost 100% in the majority of populations. Alloantibodies to high prevalence antigens cause difficulties with antibody identification and exclusion in serological investigations.
Case Presentation: This review describes the management of four antenatal cases where the presence of alloanti-Hy had been identified.