Implications for urgent transfusion of uncrossmatched blood in the emergency department: The prevalence of clinically significant red cell antibodies within different patient groups.

Abstract

To define the prevalence of alloantibodies as a factor of age and underlying clinical disease, with particular relevance to the prediction of the safety of uncrossmatched blood in different demographic groups. A retrospective review was conducted of all immunohaematological studies on blood samples submitted to the blood bank of a tertiary referral hospital between January 1998 and December 1999. A total of 27 968 antibody screens in 15 966 patients were analysed. When only clinically significant antibodies were considered, the total alloimmunization prevalence was 1.9% and the prevalence of antibodies capable of causing an immediate transfusion reaction was 0.6%. The prevalence of antibodies capable of causing an immediate transfusion reaction was 0.1% in the under 30 years of age group. Clinically significant antibodies were found in 5.1% in the haematology and oncology unit patients. The risk rises with age and female sex. We conclude that uncrossmatched blood is associated with low risk in patients < 30 years of age. The knowledge that patients have not been exposed to previous transfusion or pregnancy will reduce the risk even further.