ABO BLOOD GROUPING DISCREPANCIES AMONG PATIENT SAMPLES AT A TERTIARY CARE CENTRE IN CHENNAI: A DESCRIPTIVE RECORD-BASED STUDY

Abstract

Background: ABO discrepancies occur when there is a mismatch between forward and reverse grouping or an unexpected reaction prevents definitive group assignment and reporting. In patients, age, disease, treatment, transfusion, and unexpected antibodies may alter antigen or antibody reactions. Methods: This study is a descriptive, record-based analysis using all 17,940 patient blood-grouping samples received from outpatient and inpatient services at a tertiary care centre in Chennai between 1 November 2023 and 31 December 2024 as the workload denominator. Blood-donor samples and neonatal or infant samples for which reverse grouping was not performed were excluded from discrepancy assessment. Samples with discordant or unexpected reactions on automated testing were re-investigated by tube testing and additional serology as indicated. Grouping discrepancies were classified into Groups I, II, III &IV and summarised using frequencies and percentages. Results: 34 ABO grouping discrepancies were identified, with a prevalence rate of 0.19% (34/17,940). Group I was the most common type (16/34; 47.06%), followed by Group IV (12/34; 35.29%) and Group  II (6/34; 17.65%); no Group III discrepancy was detected. The key underlying causes identified included chemotherapy or immunosuppressive therapy (7), ABO subgroup or altered antigen expression (3), non-ABO alloantibodies (3), cold-reactive antibodies (3), and recent transfusion (2). Conclusion: Overall ABO discrepancies are uncommon, yet they are clinically important. The predominance of Group I and IV discrepancies in the study reflected patient-related serological interference, emphasising the importance of correlating serological findings with the patient’s clinical history, underlying disease, treatment history, transfusion history and relevant laboratory parameters for accurate resolution of ABO grouping discrepancies.