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Providing Red Cells for Massively Transfused Patients with Antibodies

In emergency transfusion situations, full compatibility testing should be completed before transfusion whenever possible. Occasionally, a patient with an alloantibody may be massively hemorrhaging and the transfusion service does not have time to screen for antigen negative units. In this situation, the medical director of the transfusion service should discuss the case with the physician caring for the patient. The urgency of the transfusion needs to be balanced against the risk of a hemolytic transfusion reaction.

The perceived risk to benefit ratio may be altered by knowledge of the hemolytic potential of the red cell antibody. Not all crossmatch-incompatible RBC transfusions result in immediate adverse transfusion reactions and/or significantly shortened survival of transfused RBCs. Examples include autoimmune hemolytic anemia, naturally occurring antibodies, and certain antibodies that do not react at 37ºC, such as anti-P1, anti-M, anti-Lua, anti-Lea and anti-Leb. With many of these red cell antibodies, the risk of transfusing serologically incompatible RBCs may be less than the risk of withholding transfusion.

When patients are being massively transfused, medical exceptions for patients with RBC antibodies may need to be implemented. Close communication with the clinical services and medical director of the Blood Bank is critical when this occurs. If time and availability permit, continue providing antigen negative units. If not, use the following guidelines.

For the purpose of this document, massive transfusion is defined as a patient receiving at least10 units of RBCs within 12 hours. If bleeding is massive and antigen typing cannot be done due to inadequate time, immediate exsanguination exceeds the risk of incompatibility outside of ABO. In this situation:

  1. Ignore clinically insignificant antibodies (Lewis, M, P1, Lu)
  2. Ignore undetectable (historical) antibodies, with the exception of Kidd.
  3. Obtain a new sample and perform an antibody screen to determine if the antibody has been diluted enough to become undetectable. If so, ignore this antibody. Follow up after the patient has stabilized to assess for possible delayed hemolytic process (check sample for hemolysis and perform a DAT).
  4. Try not to ignore detectable antibodies that are highly likely to be associated with overt hemolytic reactions (Kell, Kidd, Duffy, anti-D)
  5. Continue trying to obtain antigen negative units to be used once the majority of the bleeding is controlled (requires communication with OR/Anesthesia).
  6. When bleeding or blood use slows down, switch back to partial, and, if possible, fully compatible units. 
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