Impact of haemoglobin vesicles on pretransfusion testing and mitigation strategies

BACKGROUND AND OBJECTIVES: Haemoglobin-based oxygen carriers (HBOCs) are intended to treat major bleeding, particularly in emergencies. While haemoglobin vesicles (HbVs)-liposome-encapsulated haemoglobin with a long shelf life-and other HBOCs can cause colour-related interference in chemistry testing, their effect on standardized pretransfusion assays remains unclear. MATERIALS AND METHODS: We evaluated the impact of HbVs in blood on routine pretransfusion testing, including ABO blood group/Rhesus D (RhD) typing, antibody screening and cross-matching, using tube and column agglutination techniques on samples collected from 10 healthy individuals and one patient with anti-E antibodies. Whole blood was mixed with HbVs at 9:1 ratio for each sample. RESULTS: Plasma treated with HbVs developed a dark-red colouration, which interfered with the agglutination assessment. Manual replacement or automated washing of plasma containing HbVs effectively restored test clarity without compromising the accuracy of tube-based assays for reverse ABO/RhD typing, antibody screening or major cross-matching. In contrast, the washing process could not be applied to column-based techniques. No interference was observed between the HbVs and commonly used reagents. CONCLUSION: Tube-based pretransfusion testing with manual replacement or automated washing procedures is recommended for accurate compatibility assessment of blood samples treated with HbVs. However, further validation is required for broader clinical application.