Abstract: Objective To observe the effect of mixed red blood cells with different ratios of A/O on blood type identification, and select the appropriate method to accurately determine the blood type after type A-supply to O hematopoietic stem cell transplantation. Methods Red blood cells mixed in different proportions of A/O were accurately prepared, and the blood type was identified by the test tube method of saline medium, the microcolumn gel carding method of low-ion liquid medium and flow cytometry. Results When the ratio of A cell/A cell+O red blood cell was 0.1%, small agglutination could be observed by tube method; When the proportion was 3%, type A red blood cells appeared in gel cards; At 3%~15%, the blood type card presents a double group of AB type, and the flow cytometry results can identify the positive of B type as false positive. Conclusion The test tube method combined with microscopic examination is the most accurate and sensitive method for identifying blood type; Flow cytometry can identify the false positive results of micro column gel blood type cards.

Key words: ABO blood group incompatibility, Hematopoietic stem cell transplantation, Blood type identification