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Blood Transfusion

Blood Groups and Compatibilities

    • ABO blood group

      ABO is the most important blood group system. Transfusion with ABO incompatible red cells can lead to severe and potentially fatal transfusion reactions. 

      The ABO blood group system contains four different ABO blood groups (see Table 1) and is determined by inherited antigens expressed on red cells (e.g., A or B antigens). 

      Children develop naturally occurring red cell antibodies (anti-A or anti-B) against the inherited A or B antigen that are not expressed on their own red cell. These naturally occurring antibodies can attack and destroy red cells carrying the corresponding antigen. 

       ABO blood group   Antigen(s) present on red cell  Antibodies present in plasma 
       Group O  -  anti-A and anti-B 
       Group A  A antigen   anti-B
       Group B  B antigen   anti-A
       Group AB  A and B antigens   - 


      If ABO incompatible red cells are transfused (e.g., A red cells to group O recipient), severe red cell haemolysis can occur. This may result in complement activation, shock, renal failure, disseminated intravascular coagulopathy (DIC) & death.

      Rh blood group

      The most significant Rh antigen is D.  When the D antigen is present on the red cell surface, the red cells are called D positive.  Approximately 84% of the Australian population are D positive.  The remaining 16% of the population that lack the D antigen are called D negative.

      D is highly immunogenic. Antibodies (anti-D) may occur after an individual is exposed to D antigens via transfusion, pregnancy or organ transplantation. These antibodies are clinically significant and can cause haemolytic transfusion reactions and result in haemolytic disease of the fetus and newborn during pregnancy. 

      D negative females of child-bearing age should receive D negative red cells.

      D positive individuals should receive D positive red cells unless these are not available or are deemed unsuitable (e.g., HSCT or extended phenotype matching in sickle cell disease). 

      If transfusion of D positive red cells to a D negative recipient, the haematologist should be consulted and consideration given for the administration of RhD immunoglobulin. Note: Platelets contain red cells and therefore if D positive platelets are transfused to a D negative female of childbearing potential, consider RhD immunoglobulin prophylaxis. 

      Blood compatibility 

      It is preferable for patients to receive red cells and platelets of the same ABO and D group.  However, if ABO and D identical products are not available, a patient may be offered an alternate compatible product (see below)  

      Red cell compatibility 
       Patient ABO group            Best option                                                                                                                                                                             OK to use  Never use 
       Unknown 

       O negative 

      In an emergency when O negative red cells are not available, O positive red cells may be administered to male patients. 

      		   -                                                                                  A, B, AB                                                                                                          
       O  O   -   A, B, AB 
       A  A  O   B, AB 
       B  B  O    A, AB 
       AB  AB  O, A, B     - 


      D compatibility - red cells and platelets
      Patient D type                    Best option                                                                                                                                                                              OK to use  Never use   
       D negative            D negative                                                                                            -                                                                                    D positive*                                                                                                   
       D positive  D positive   D negative   -

      * In an emergency, when D negative components are not available, transfusion should not be withheld. D negative males may receive D positive red cells but should be monitored for haemolysis and are a risk of developing anti-D antibodies. Suggest DAT and BGAB following transfusion. 

      Platelet compatibility

      Platelets contain red cells and therefore D compatible products are preferred. If D positive platelets are given to a D negative female of child-bearing potential, then consider RhD immunoglobulin.  
      Patient ABO group          Best option                                                                                                                                                                    OK to use                                                            Avoid if possible                                                                                    
       Unknown                

       O negative (low titre#) or A negative (low titre)              

      		   -                                    B, AB                                                                    
       O                                O         A   B, AB 
       A  A   B, O    AB
       B  B   A, O   AB
       AB  AB (not routinely available)    A, B    O

      # low levels of anti-A/B 

      Plasma compatibility (Fresh frozen plasma and Cryoprecipitate)

      Plasma components should be compatible with the ABO group of the recipient. Plasma components of any D type can be given irrespective of the recipient's D status. RhD immunoglobulin is not required. 
       Patient ABO group     Best option                                                                                                                                                           OK to use                                                            Avoid if possible                                                                         
       Unknown 

       AB 

      In an emergency when AB plasma is not available, A (low titre #) plasma may be given with caution^. 

      		  -  B
       O  O  A, B, AB  -
       A  A  AB  B
       B  B   AB  A 
       AB                AB  -   A, B 

      # low levels of anti-A/B 

      ^ ANZSBT Guidelines for Transfusion and Immunohaematology Laboratory Practice (Revised 1st edition 2020) and BSH Transfusion for Fetuses, Neonates and Older Children Guidelines (2016) recommend AB plasma for neonates. Life-saving transfusions should not be withheld if AB plasma is not available.