If an antibody screen is positive, the next test to determine the exact alloantibody is which?

If an antibody screen is positive, the next test to determine the exact alloantibody is which?

• A. Antibody identification panel
• B. Direct Coombs test
• C. Crossmatch
• D. ABO/Rh typing

Answer: (A)

Identifying the specific alloantibody requires an antibody identification panel. When the screen is positive, it shows that there are unexpected antibodies in the patient’s plasma, but it doesn’t reveal which one. The identification panel tests the patient’s serum against a spectrum of reagent red cells with known antigen profiles. By examining the pattern of reactions across cells with different antigens, you can deduce the exact antibody specificity. This information is essential for selecting compatible donor units and for anticipating or preventing transfusion reactions. The other tests serve different purposes: the direct Coombs test detects antibodies or complement on the patient’s own red cells, not the exact antibody in circulation; crossmatching checks compatibility of a specific donor unit after the antibody is known; ABO/Rh typing determines antigen status to guide transfusions, not the antibody’s identity.

Identifying the specific alloantibody requires an antibody identification panel. When the screen is positive, it shows that there are unexpected antibodies in the patient’s plasma, but it doesn’t reveal which one. The identification panel tests the patient’s serum against a spectrum of reagent red cells with known antigen profiles. By examining the pattern of reactions across cells with different antigens, you can deduce the exact antibody specificity. This information is essential for selecting compatible donor units and for anticipating or preventing transfusion reactions. The other tests serve different purposes: the direct Coombs test detects antibodies or complement on the patient’s own red cells, not the exact antibody in circulation; crossmatching checks compatibility of a specific donor unit after the antibody is known; ABO/Rh typing determines antigen status to guide transfusions, not the antibody’s identity.