ABSTRACT
Background & objectives: Red blood cell alloimmunization is common in patients receiving multiple blood transfusions. Since the probability of repeat transfusion increases with longer life expectancy, it is important to study to which extent alloimmunized patients with a history of transfusion are prone to form alloantibodies after transfusion events. The aim of this study was to retrospectively analyze the alloimmunization against RBCs among transfused patients who were to undergo elective surgery in Tehran, Iran. Methods: A total of 3092 occasionally transfused patients, who were to undergo elective surgery, in four hospitals in Tehran were included in the study. For patients with alloantibodies, the data about sex, date of birth, history of transfusion, surgery, abortion and alloantibody specificity were collected. Results: Clinically significant alloantibodies were found in 30 patients. The presence of positive antibodies in the patients for whom cross-match had been done was one per cent. Most of them had surgery history or transfusion record during the preceding year. The three most frequent alloantibodies were anti-K (23.53%), anti- E (20.59%) and anti-c (17.56%). Interpretation & conclusions: The most common clinically significant alloantibodies identified in men and women were anti-K and anti-E, respectively. The most common causes of alloimmunization for men were surgery history and transfusion record and for women pregnancy.