If a hemolytic transfusion reaction is suspected, which procedure should be performed immediately?

• A. Direct antiglobulin test on the post-transfusion specimen
• B. Indirect antiglobulin test on the post-transfusion specimen
• C. Crossmatching again
• D. ABO typing only

Answer: (A)

In a suspected hemolytic transfusion reaction, the immediate step is to perform the direct antiglobulin test on the post-transfusion blood sample. The DAT detects antibodies or complement bound to red blood cells in the patient’s circulation, offering direct evidence that immune-mediated hemolysis is occurring due to the transfusion. A positive DAT confirms that red cells are being attacked in vivo, which is the hallmark of an acute immune reaction and guides urgent management (stop the transfusion, support the patient, investigate the alloantibody/compatibility issue).

The indirect antiglobulin test looks for free antibodies in plasma and isn’t testing what’s currently coating the patient’s red cells, so it isn’t the best immediate test in this scenario. Rechecking crossmatches or performing ABO typing alone won’t establish that in vivo hemolysis is taking place. The DAT on the post-transfusion specimen directly demonstrates the immune process causing the reaction.