Which crossmatch step is most appropriate for quickly assessing ABO compatibility before transfusion?

• A. Immediate spin crossmatch
• B. AHG crossmatch
• C. Donor antibody screen
• D. Type & Screen

Answer: (A)

Immediately spin crossmatching tests ABO compatibility fastest by mixing recipient plasma with donor red cells at room temperature and looking for agglutination within minutes. Because ABO antibodies are mainly IgM and react at room temperature, any incompatibility shows up right away, letting you decide quickly whether a donor unit can be used for transfusion. If the test is negative, ABO compatibility is demonstrated for that donor unit and you can proceed, with further testing only if time allows or if non-ABO antibodies are a concern.

The AHG crossmatch adds the antiglobulin step to detect other antibodies but takes longer, so it’s not the quickest way to confirm ABO compatibility. The donor antibody screen and Type & Screen provide information about antibodies in donor blood or general compatibility in advance, but they don’t confirm a specific donor unit’s ABO compatibility in the moment of transfusion.