RHD‐negative red cells may be avoided for patients with ambiguous serologic typing for the RHD antigen

Abstract

AbstractBackground and ObjectivesSerologic typing with monoclonal anti‐D is mandatory for RHD antigen determination before transfusion, but due to aberrant (weak or partial) variants of RHD, results may be ambiguous and molecular RHD‐typing is required. Before that, RHD‐negative (RHD –) red blood cells concentrates (RBCs) shall be transfused to avoid anti‐D formation, which probably leads to wastage of RHD ‐ RBCs.Study Design and MethodsAll patients with ambiguous results in serologic RHD‐typing and molecular RHD‐typing were assessed retrospectively. The proportions of patients at risk for anti‐D formation and the proportion of RHD ‐ RBCs transfused unnecessarily were evaluated for the following transfusion strategies: (1) RHD‐positive (RHD + )RBCs for all patients, (2) RHD + RBCs for patients with at least 2+ reaction with anti‐D, (3) RHD + RBCs for patients with C and/or E in their RHCE‐phenotype, (4) RHD + RBCs for patients with C and/or E and at least 2+ reaction, and (5) RHD ‐ RBCs for all patients.ResultsA total of 112 patients were included. Most had weak D type 1–3 and a minority had other, rare RHD variants. The risk of anti‐D formation was 4.5%, 2.9%, 1.8%, 1.0%, and 0% for strategies 1–5, respectively. The proportion of RHD ‐ RBCs transfused unnecessarily was 0%, 49.5%, 0.9%, 50.5%, and 95.5%.ConclusionTransfusing patients with a C and/or E in their RHCE‐phenotype with RHD + RBCs resulted in a very low risk of immunization while avoiding wastage of RHD ‐ RBCs. Therefore, this strategy should be used for some patients with ambiguous results in serologic RHD‐typing and pending results of molecular RHD‐typing.