*Clinical pathology, *Pathological laboratories, *Retrospective studies, *Immunomodulators, *Comparative studies, *Descriptive statistics, *Erythrocytes, *Diagnostic errors

Introduction: Interferences on red blood cells (RBCs) measurement and the associated parameters in haematology analyzers are very common. Many sources of interferences are described but their management remains uncertain depending on the measurement system; we aimed at developing an optimized scheme allowing the accurate management of most interferences affecting RBCs, based on the alternative "optical" parameters from SYSMEX XN-10. Methods: Samples from 12 groups of relevant interferences were analysed and compared with a control group allowing (1) the determination of deviation thresholds beyond which an interference is likely, and (2) the development of two flowcharts for their subsequent management. These flowcharts were then evaluated among a bank of retrospective typical cases of interferences and in the routine flow of the laboratory. Results: After verifying the excellent agreement between standard and alternative parameters, the comparative study between analytical channels allowed to determine an acceptable deviation and then discriminate technical concerns caused by cold agglutinins, leukocytosis and plasma-related interferences. This led to the development of flowcharts ensuring the accurate management of these interferences, whether MCHC is <320 or >365 g/L. These proposed flowcharts allowed the correction of 63/65 historical confirmed interferences cases (97%). Furthermore, they corrected 18 results among 901 unselected prospective samples. Conclusion: The resulting flowcharts allow a relevant correction for most common interferences affecting RBCs and are now definitively included in the routine analytical management and will be directly incorporated in the middleware of the laboratory. [ABSTRACT FROM AUTHOR]

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