JPAC Joint United Kingdom (UK) Blood Transfusion and Tissue Transplantation Services Professional Advisory Committee

2: Basics of blood groups and antibodies


  • ABO-incompatible red cell transfusion is often fatal and its prevention is the most important step in clinical transfusion practice.
  • Alloantibodies produced by exposure to blood of a different group by transfusion or pregnancy can cause transfusion reactions, haemolytic disease of the fetus and newborn (HDFN) or problems in selecting blood for regularly transfused patients.
  • To prevent sensitisation and the risk of HDFN, RhD negative or Kell (K) negative girls and women of child-bearing potential should not be transfused with RhD or K positive red cells except in an emergency.
  • Use of automated analysers, linked to laboratory information systems, for blood grouping and antibody screening reduces human error and is essential for the issuing of blood by electronic selection or remote issue.
  • When electronic issue is not appropriate and in procedures with a high probability of requiring transfusion a maximum surgical blood ordering schedule (MSBOS) should be agreed between the surgical team and transfusion laboratory.

There are more than 300 human blood groups but only a minority cause clinically significant transfusion reactions. The two most important in clinical practice are the ABO and Rh systems.