Introduction: The less commonly encountered blood groups include A1 negative, A2 positive, A2 negative, B negative, O negative, A1B negative, A2B positive, A2B negative, and the Bombay blood group in both Rhesus factor (Rh) positive and Rh negative phenotypes. The frequency of ABO and Rh groups varies across populations and regions. Aim: To examine the prevalence of less common blood groups, namely A1-, A2+, A2-, O-, A1B-, A2B+, A2B-, and Bombay blood group in both Rh positive and Rh negative phenotypes. Materials and Methods: A retrospective, cross-sectional study was conducted over a period of five years from January 2018 to December 2022, involving 36,674 blood donors from a tertiary care hospital at Department of Pathology, SDMCMSH, Dharwad located in the north Karnataka region, India. Blood grouping was performed using the gel card method, and further subtyping was conducted using specific antisera. Results were analysed and presented as frequencies and percentages. All blood groups were tabulated, and the percentages of each blood group were calculated, including A1+, A2+, A1-, A2-, A1B+, A2B+, A1B-, A2B-, B+, B-, O+, O-, Bombay blood group Rh positive, and Bombay blood group Rh negative. Results: Of the 36,674 donors, 34,803 (94.89%) were Rh positive. The most common blood group was found to be O positive, with 11,897 donors (32.43%), followed by B positive with 10,658 (29.06%), A1 positive with 9,306 (25.37%), and A1B positive with 2,606 (7.10%). The less common blood groups included A1 negative (467, 1.27%), A2 positive (45, 0.12%), A2 negative (8, 0.02%), B negative (614, 1.67%), O negative (614, 1.67%), A1B negative (133, 0.36%), A2B positive (282, 0.76%), A2B negative (35, 0.09%), and the Bombay Oh phenotype (Rh positive) with 9 (0.02%) of the total. Conclusion: This study highlights the prevalence of less commonly encountered and rare blood groups, ensuring adequate maintenance of inventory to meet needs, especially during adverse situations such as road traffic accidents, postpartum haemorrhage, and other medical, surgical, critical care emergencies, and mass casualties involving these rare blood groups.
Shigli et al. (Tue,) studied this question.