Transfusion medicine handbook

4. Blood Components

4.3 RhD Antigen

After ABO, the RhD antigen ranks next in importance for transfusion. Patients and blood donors are routinely typed for the RhD antigen and on the basis of its presence or absence are called either RhD positive or RhD negative.

Antibodies to the RhD antigen only occur as a result of transfusion or pregnancy in individuals who are RhD negative. The RhD antigen is highly immunogenic and an RhD negative person only needs to be exposed to a small volume of RhD positive red cells to stimulate production of anti-D.

Red cell and platelet transfusions are normally of the same RhD type as the patient. RhD negative components may be given to RhD positive recipients without any risk of immunisation.

In life-threatening situations or where RhD identical components are not readily available, it may be necessary to transfuse RhD negative recipients with red cells or platelets from an RhD positive donor. In these circumstances the blood bank will provide guidance. It is essential that the treating clinician is informed and the appropriateness of administration of prophylactic anti-D immunoglobulin considered. In the case of RhD negative females with child-bearing potential, transfusion of RhD positive red cells must only be considered following discussion with a NZBS Transfusion Medicine Specialist / Medical Officer.

If supplies of RhD negative red cells are low, RhD positive red cells may be provided by the blood bank for RhD negative males and for females beyond reproductive years.

Residual red cells in RhD positive platelet components may sensitise RhD negative patients to form anti-D. When platelet components from a RhD positive donor are transfused into a RhD negative recipient, in particular females of childbearing age or female children, prophylactic anti-D immunoglobulin must be considered.

Section 5.4.7: Rh(D) Immunoglobulin-VF contains guidelines on dosing of prophylactic anti-D following transfusion of RhD positive blood components.