BLOOD GROUP COMPATIBILITY

Blood grouping identifies the ABO and Rh type of a recipient or donor. This grouping ensures that the patient receives compatible blood products.

The ABO Blood Group System The ABO blood group is determined by the A or B antigen attached to the membrane of the red blood cell. Group A persons inherit the A antigen and make anti-B antibodies which destroy cells carrying B antigens. Group B persons inherit the B antigen and make anti-A antibodies which destroy cells carrying A antigens. Group AB persons inherit the A and B antigen and do not make either A or B “antibodies”. Group O persons do not inherit the A or B antigen and make “antibodies” which destroy cells carrying A or B antigens. Antibodies against A and B antigens are produced spontaneously in the plasma within the first few months of life.

Blood Group Antigen on Red Cell Antibodies in Plasma A A antigen Anti-B B B antigen Anti-A AB both A & B antigens neither Anti-A or Anti-B O neither A & B antigens Anti-A and Anti-B

Rhesus (Rh) Blood Group System The Rh type is determined by the presence or absence of the Rh “D” antigen on the red cells. • Rh positive – D antigen is present • Rh negative – D antigen is absent Unlike the ABO system, there are no naturally occurring Rh antibodies. Anti-D is produced when an Rh negative individual is exposed to Rh positive red cells (e.g. through transfusion or pregnancy). Rh antigens are carried on red cells only. Rh compatibility criteria apply only to products containing red cells (whole blood, packed red cells and platelets).

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BLOOD GROUP COMPATIBILITY

Selection of Blood Components Ideally, transfusion of blood components of the patient’s own blood group is always best. If the specific blood group is not available, hemolytic transfusion reactions can be avoided by transfusing blood components which are ABO compatible with the patient’s blood group. Alternate blood groups below are listed in the order of selection by the Transfusion Medicine Laboratory. Cryoprecipitate contains little plasma. ABO compatible is preferred but not required. Platelets which are ABO incompatible are tested for high titre anti-A or anti-B prior to issue.

ABO Compatibility - Red Cells, Plasma & Cryoprecipitate Patient Group Red Blood Cells Plasma Cryoprecipitate O Pos O pos, O neg O, A, B, AB O, A, B, AB O Neg O neg A Pos A pos, A neg, O pos, O neg A, AB A, AB, B, O A Neg A neg, O neg B Pos B pos, B neg, O pos, O neg B, AB B, AB, A, O B Neg B neg, O neg AB Pos All groups AB AB, A, B, O AB Neg AB neg, A neg, B neg, O neg Unknown O neg AB AB

ABO Compatibility - Platelets Patient Group 1st Choice 2nd Choice 3rd Choice O O A or B or AB A A AB B (Negative for high titre anti-A) OR O (Negative for high titre anti-A) B B AB A (Negative for high titre anti-B) OR O (Negative for high titre anti-B) AB AB A (Negative for high titre anti-B) O (Negative for high titre anti-A OR and anti-B) B (Negative for high titre anti-A) Unknown AB Rh positive patients may receive Rh positive or Rh negative platelets. Rh negative patients should receive Rh negative platelets. If there is a shortage of Rh-negative platelets, Rh-positive platelets may be given. Rh immune globulin (RhIg) may be given in consultation with hematopathologist.

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