RESUMEN
OBJECTIVE@#To establish the diagnostic process of low titer blood group antibody in the occurrence of adverse reactions of hemolytic transfusion.@*METHODS@#Acid elusion test, enzyme method and PEG method were used for antibody identification. Combined with the patient's clinical symptoms and relevant inspection indexes, the irregular antibodies leading to hemolysis were detected.@*RESULTS@#The patient's irregular antibody screening was positive, and it was determined that there was anti-Lea antibody in the serum. After the transfusion reaction, the low titer anti-E antibody was detected by enhanced test. The patient's Rh typing was Ccee, while the transfused red blood cells were ccEE. The new and old samples of the patient were matched with the transfused red blood cells by PEG method, and the major were incompatible. The evidence of hemolytic transfusion reaction was found.@*CONCLUSION@#Antibodies with low titer in serum are not easy to be detected, which often lead to severe hemolytic transfusion reaction.