Comparative detection of red cell alloantibodies by solid‐phase red cell adherence and column agglutination technology in routine pre‐transfusion testing

Abstract Background and Objectives Detection of clinically significant alloantibodies (CSAs), particularly weak or weakly reactive antibodies, remains challenging with conventional agglutination methods and may contribute to delayed haemolytic transfusion reactions (DHTRs). Antibodies known to be associated with DHTRs or reduced red cell survival were classified as CSAs. We aimed to compare solid‐phase red cell adherence (SPRCA) and column agglutination technology (CAT) for antibody screening and identification. Materials and Methods In this retrospective study, 33,340 antibody screens (September 2023–March 2025) were evaluated by SPRCA and CAT. Reactive or inconclusive samples underwent antibody identification by both methods with enzyme‐phase testing. Agreement was assessed using positive (PPA) and negative percent agreement (NPA). Results Of the 33,340 samples, 547 (1.6%) were screen‐positive or inconclusive. Screening agreement was high (PPA 98.5%, NPA 99.8%). Of the 546 evaluable samples, 464 (84.8%) were reactive by both methods. At least one CSA was identified in 405/546 samples (74.2%). SPRCA detected CSAs in 398/405 samples (98.3%) compared to 331/405 (81.7%) by CAT, and identified 490 antibodies versus 401 by CAT (450 after enzyme enhancement). CAT did not detect 102 CSAs in 86 samples detected by SPRCA. SPRCA did not detect 13 CSAs in nine samples detected by CAT. Most additional antibodies detected by SPRCA belonged to Rh, Kell, Kidd and Duffy systems, with largest relative gains observed for Duffy (60%), Kidd (45%) and Kell (44%) antibodies. Conclusion SPRCA demonstrated greater analytical sensitivity than CAT for detecting weakly reactive CSAs, particularly in the Rh, Kidd and Kell systems. These findings support the potential utility of SPRCA as a complementary method in selected clinical settings.