Which test should be performed on the post-transfusion specimen when a transfusion reaction is suspected to evaluate immune involvement?

Which test should be performed on the post-transfusion specimen when a transfusion reaction is suspected to evaluate immune involvement?

• A. Direct antiglobulin test
• B. Indirect antiglobulin test
• C. Coombs test on pre-transfusion
• D. PCR blood typing

Answer: (A)

To evaluate immune involvement in a suspected transfusion reaction, you look for antibodies or complement bound to a patient's red blood cells in vivo. This is detected by the direct antiglobulin test (DAT), also known as the direct Coombs test. The test uses anti-human globulin to see if IgG or C3d are coating the patient's red cells in the post-transfusion specimen. A positive DAT supports immune-mediated hemolysis, such as an acute hemolytic transfusion reaction caused by alloantibody or autoantibody activity against donor RBCs. In contrast, indirect antiglobulin testing screens the patient’s serum for antibodies that could react with donor cells and is typically used before transfusion, not to assess a reaction after it starts. PCR blood typing is for determining an individual’s blood group antigens and isn’t used to evaluate a transfusion reaction.

To evaluate immune involvement in a suspected transfusion reaction, you look for antibodies or complement bound to a patient's red blood cells in vivo. This is detected by the direct antiglobulin test (DAT), also known as the direct Coombs test. The test uses anti-human globulin to see if IgG or C3d are coating the patient's red cells in the post-transfusion specimen. A positive DAT supports immune-mediated hemolysis, such as an acute hemolytic transfusion reaction caused by alloantibody or autoantibody activity against donor RBCs. In contrast, indirect antiglobulin testing screens the patient’s serum for antibodies that could react with donor cells and is typically used before transfusion, not to assess a reaction after it starts. PCR blood typing is for determining an individual’s blood group antigens and isn’t used to evaluate a transfusion reaction.