Anti-M Antibody in Blood Transfusion: An Underestimated Factor in Service Delays and Expenditures.

Background and objective The effect of anti-M (IgM or IgG) on transfusion services is hardly addressed in the literature. Here, the prevalence of clinically significant anti-M among the donor population and patients and their impact on turnaround time for the issue of blood units and cost was analysed. Methods A retrospective review of immunohaematological records from blood donors and patient electronic medical records at a tertiary care hospital, Odisha, India over a two-year period was conducted to assess the impact of anti-M antibody developed in donors or patients on blood transfusion services. Results Anti-M antibodies were identified in approximately one in every 7,155 blood donations and in one in 2,380 patients (20 out of 47,613 transfusion requests). These antibodies were detected across all patient age groups (ranging from four to 80 years) and in four young donors aged 18 to 30 years. Among the identified cases, the anti-M antibody was of the IgM + IgG type in three donors and 13 patients. Resolving blood group discrepancies due to anti-M required an average of eight hours and necessitated the expertise of a certified immunohematology (IH) technician, as well as advanced testing procedures. This led to a statistically significant increase (p < 0.05) in testing costs - approximately 10-fold higher than routine testing. The median turnaround time for issuing compatible blood units increased significantly (Median: 24 hours, p < 0.05) for hospitalized patients. Two cases with anti-M were suspected to have the M variant with the M-positive phenotype, not degraded by papain treatment. Twenty units were found to be M-negative after typing 247 units for 13 patients. The scheduled surgical procedure was delayed by a median of two days (range one to eight days) in eight cases to make an M-negative compatible blood unit available. These delays further escalated pretransfusion testing costs and extended hospital stays. In one instance, an M-negative unit could not be found even after testing 48 units, necessitating referral to another centre. Conclusion The presence of clinically significant anti-M antibodies in our population resulted in transfusion and surgical start time delay, a 10-fold increase in cost for pretransfusion testing. Establishing advanced centres with an M-negative donor database and promoting inter-centre collaboration could help address the challenges of finding the required number of M-negative units.