Prevalence of ABO and Rhesus blood groups in Blood donors: A retrospective study from a tertiary care blood bank in Pondicherry.

Introduction: The ABO blood group system was the first human blood group system discovered by Austrian scientist Karl Landsteiner in 1901. The ABO blood group system is divided into four blood types on the basis of presence or absence of A and B surface antigens A and B antibodies presence in the plasma. Positive and Negative of the blood group determines by presence or absence of the D antigen.. Objectives: This study was carried out to determine the distribution pattern of blood groups among blood donors at a tertiary care hospital of Puducherry Materials and Methods: It is a retrospective study done a period of 5 years from May 2017 to May 2022 that includes the 9062 blood donors. Blood group done as per the standard operative procedure. Data on the ABO and Rh blood group type of all blood donors was collected and analysed. Result: The most common ABO blood group type was Group O (38%) followed by group B (33.5%), group A (21.6%) and group AB (6.9%) and one Bombay blood group. The distribution of Rh(D) blood group type revealed 92.5% as Rh-positive and 7.5% as Rh-negative. Conclusion: The most common ABO blood group type in our region (Puducherry) is Group O followed by B and A while, AB and Bombay groups are the least common type. Knowledge of the blood group distribution pattern is essential for the effective delivery of blood banking services.