Prevelance of ABO Discrepancies and Its Classification in Blood Donors at Regional Blood Centre, Karachi - Abstract
Background: ABO and Rh systems are the most important blood group systems of human body. More than 400 blood group systems have been reported, however majority of them are not clinically significant. The ABO group system comprises of antigens represented by forward blood grouping and antibodies represented by reverse blood grouping. Reverse blood grouping is usually done to verify the results of forward blood grouping. ABO discrepancy is defined as a difference of result between forward and reverse group and has been reported to be around 0.15- 0.19%. ABO discrepancies are divided into 4 types. Type 1 discrepancy include those having missing antibodies in reverse grouping and are most common. Type 2 discrepancy include missing antigens in forward grouping. Type 3 are those because of abnormalities in plasma or proteins and type 4 is represented as miscellaneous. Aims and Objectives: The aim of this study was to calculate the frequency of ABO discrepancies in healthy blood donors, its classification into different types and identification of different subgroups in order to provide safe blood to the patients. Material and Methods: Descriptive, cross sectional study was conducted at Regional blood centre Karachi from January 2020 to August 2023.78,623 donors were enrolled in the study. Blood samples were collected in di- potassium ethylene diamine tetra acetic acid (K2 EDTA) and yellow gel top vacutainers. Blood grouping was performed by a technician/ technologist by tube method and was reconfirmed by a senior technologist. Results: 78623 samples were included in the study, with majority of the males. The mean age of blood donors was 28.5 years. ABO discrepancy was found in 108 cases (0.13%). 4 groups of ABO discrepancies were made according to AABB. Most common ABO discrepancy was type 4 (46.3%) followed by type 1 (37.0%). Type 2 and type 3 were 11.1% and 5.6% respectively. Most common blood group associated with ABO discrepancies was O positive, followed by A positive (p value 0.001). Most subgroups were associated with a followed by B. Conclusion: ABO blood grouping remains the most important testing in the blood donors. The significance of determining the actual blood group lies in the fact that safe blood transfusion should be the utmost priority. Complete blood grouping along with resolution of discrepancies will continue to be a significant feature in providing safe blood to the patients and preventing them from fatal transfusion reactions.