Question

A blood bank using the ECHO found a discrepant result on a donor sample that was tested for weak D. Prior donor records showed the result as weak D-positive, whereas current testing was weak D-negative. A review of the records indicated that previous testing was performed in the tube, before implementing the automated system.

What are possible causes of these differing results, and how should the problem be resolved?

Answer 1

Weak D is a different phenotype of Rh D that shows weak antigen proportion as test result. This antigen has a low immunogenicity that caues the result to be discrepent. This reports ultimately result in wrong grouped blood to be transfused to an individual resulting in serious transfusion related adverse events. Molecular tests such as Sensitive gel system could be used to differentiate partial and weak D and grouping and typing of blood groups that gives results which are consistent. I order to avoid alloimmunization, samples must be taken from immediate spin test that yields 1+ not more than 2 + agglutination.