Prospective study for determining the prevalence of causes of ABO blood group discrepancies and to establish a clinical classification in a tertiary care transfusion center

1)      ABOgrouping is an essential step of immunohematology workup. Matching of bloodgroup antigens is important while providing transfusion support, in transplantationsto decrease the chances of graft rejection. Timely resolution of ABOdiscrepancy is an important step of patient management.

ABOdiscrepancy is when the reactions in forward and reverse grouping do not alignwith each other, usually due to unexpected positive or negative reactions ineither. This can be due to intrinsic problems with either the antibodies orRBCs in the sample and also due to technical errors.

Basedon the traditional way of classification of ABO discrepancy, there are fourtypes of discrepancies. Type 1 has unexpected reactions in reverse grouping.Type 2 has unexpected reactions in forward grouping. Type 3 has unexpectedreactions due to rouleaux formation caused by protein abnormalities. Type 4 isdue to miscellaneous causes.

Bloodgrouping is an essential step to be done on both donor’s and patient’s bloodbefore issuing blood to the patient. Discrepancies must be resolved firstbefore reporting the blood groups to avoid cross-match incompatibility.Incompatibility between the donor’s and patient’s blood can lead to severe transfusionreactions which at times can be fatal. Most discrepancies can be resolved byserological methods. Discrepancies not resolved as so are to be resolved usingmolecular genotyping methods.

Itis important to study the incidence and prevalence of ABO discrepancies andtheir various causes. The study by Shanti et al in a tertiary care center incentral south India noted ABO discrepancies in 4.75% of total groupings. Thesewere due to subgroup A (81%), autoantibodies (14.5%) (out of which 37% were dueto cold autoantibodies and the rest due to warm and mixed type), alloantibodies(2.56%), Bombay phenotype (1.2%), ParaBombay (0.6%) andmultiple myeloma and heparin therapy (1.4%).

Withthis background, we aimed to determine the causes of ABO blood grouping discrepancyat our center. The main objective of the study is to develop a clinicallyrelevant method of classification of ABO discrepancies and to assess theappropriate resolution techniques for those categories.