Comparison of manual hematocrit determinations versus automated methods for hematopoietic progenitor cell apheresis products

BACKGROUND Allogeneic hematopoietic stem cell donor selection is based primarily on human leukocyte antigen degree of match and it often occurs without regard to the red blood cell (RBC) compatibility between donor and recipient. When major ABO-mismatched grafts are infused, it is imperative that an accurate determination of the incompatible RBC content is made to ensure that the product is safe for infusion. RBC content determination requires the hematocrit (Hct) parameter which can be obtained via manual (directly measured) or automated (calculated) methods. STUDY DESIGN AND METHODS Ninety-seven apheresis hematopoietic progenitor grafts were assessed for Hct by manual testing and by four commercially available automated hematology analyzer instruments. A clinical model was developed to assess the frequency of unnecessary RBC reductions or alteration in standard infusion practice. RESULTS Significant (p < 0.001) differences were observed where the manual Hct value was markedly lower than automated Hct values. At stringent incompatible RBC threshold of 10 mL, the number of preventable RBC reduction procedures ranged from 18% to 69%. CONCLUSION Accurate determination of RBC content of hematopoietic progenitor grafts is essential for patient safety. Despite the rapidity and convenience offered by automated Hct methods, they significantly overestimate the incompatible RBC content of grafts, which may trigger unnecessary RBC reduction procedures or split infusions. In products where automated Hct methods indicate excessive amounts of incompatible RBCs are present, we advise the performance of confirmatory testing with a manual Hct method to ensure that the automated Hct value is not a false positive.