With a direct antiglobulin test showing anti-IgG positive and anti-C3d positive, which procedure is indicated?

With a direct antiglobulin test showing anti-IgG positive and anti-C3d positive, which procedure is indicated?

• A. prewarm technique
• B. elution
• C. wash
• D. incubation at 37°C

Answer: (B)

When the direct antiglobulin test is positive for both IgG and C3d, it means red cells are coated with IgG antibodies and have compliment on their surface. To identify which antibody is bound, you perform an elution. Elution releases the bound IgG from the red cell surface, producing an eluate that can be tested against a panel to determine the antibody’s specificity. This helps distinguish whether the coating antibody is an alloantibody or an autoantibody and guides appropriate transfusion decisions. The other options aren’t aimed at identifying the bound antibody: prewarm is mainly used to enhance cold agglutinin reactions, and washing or incubation steps are part of routine testing but do not reveal the antibody specificity after a DAT.

When the direct antiglobulin test is positive for both IgG and C3d, it means red cells are coated with IgG antibodies and have compliment on their surface. To identify which antibody is bound, you perform an elution. Elution releases the bound IgG from the red cell surface, producing an eluate that can be tested against a panel to determine the antibody’s specificity. This helps distinguish whether the coating antibody is an alloantibody or an autoantibody and guides appropriate transfusion decisions. The other options aren’t aimed at identifying the bound antibody: prewarm is mainly used to enhance cold agglutinin reactions, and washing or incubation steps are part of routine testing but do not reveal the antibody specificity after a DAT.