For which of the following blood groups is it NOT necessary to run an Rh control if you are using a monoclonal/polyclonal blend anti-D?

For which of the following blood groups is it NOT necessary to run an Rh control if you are using a monoclonal/polyclonal blend anti-D?

• A. A positive
• B. O negative
• C. AB positive
• D. B positive

Answer: (A)

Rh controls are used to verify that any agglutination observed with anti-D is truly due to the D antigen and not a non-specific reaction. If the red cells are known to be Rh positive, they carry the D antigen, so anti-D will reliably cause a positive reaction. In that situation, using a monoclonal/polyclonal blend anti-D makes the reaction highly specific, and the Rh control adds little interpretive value. Therefore, for a blood group that is Rh positive (such as A positive), it’s not necessary to run the Rh control. In contrast, Rh-negative samples (lacking the D antigen) would still benefit from an Rh control to ensure the lack of agglutination isn’t due to reagent or procedural issues.

Rh controls are used to verify that any agglutination observed with anti-D is truly due to the D antigen and not a non-specific reaction. If the red cells are known to be Rh positive, they carry the D antigen, so anti-D will reliably cause a positive reaction. In that situation, using a monoclonal/polyclonal blend anti-D makes the reaction highly specific, and the Rh control adds little interpretive value. Therefore, for a blood group that is Rh positive (such as A positive), it’s not necessary to run the Rh control. In contrast, Rh-negative samples (lacking the D antigen) would still benefit from an Rh control to ensure the lack of agglutination isn’t due to reagent or procedural issues.