The following results are observed on a patient in the medical intensive care unit: IS 37 AHG SCR I 2+. 1+. 0 SCR II 2+. 1+. 0 AC 2+. 1+. 0 What should be done next?

• A. Crossmatch with a selected panel
• B. Cold autoabsorption
• C. Direct antiglobulin test
• D. Warm autoabsorption

Answer: (B)

The results show strong reactivity at immediate spin with decreasing reactivity at 37°C and no reactivity in the antiglobulin phase across the tested panels, which is the classic pattern of a cold autoantibody (IgM) causing panreactivity. This type of antibody binds RBCs at cold temperatures and can mask any underlying alloantibodies, making it hard to identify the appropriate donor antigens for transfusion.

Because of this masking effect, the appropriate next step is cold autoabsorption. By adsorbing the patient’s serum with donor red cells at cold temperature, the cold autoantibody is removed, allowing any latent alloantibodies to be revealed on subsequent antibody screening and identification. After adsorption, you can perform a more reliable antibody screen/crossmatch to select compatible units.

Crossmatching with a selected panel would be better after adsorption, not before, since the autoantibody interference would obscure results. The direct antiglobulin test isn’t the priority here given the pattern, and warm autoabsorption targets a warm IgG autoantibody, which isn’t indicated by this cold-dominant reactivity.