BACKGROUND: Most blood crossmatched in a hospital blood bank is for surgical patients, and the majority is never transfused. The maximal standard blood order schedule is used to promote efficient ordering practices for surgical patients.

STUDY DESIGN and METHODS: To ascertain the predictors of red cell transfusions for patients undergoing total hip arthroplasty, the charts of 299 adult patients undergoing primary and revision total hip arthroplasty were reviewed. A surgical blood order equation was developed for calculating the number of units of red cells that should be ordered. Stepwise regression analysis was used to determine which patient-and-case-related variables should be considered in the surgical blood order equation.

RESULTS: The significant indicators for allogeneic red cell transfusion to patients on the day of total hip arthroplasty were preoperative hemoglobin concentration, weight, age, estimated blood loss, and aspirin use. The surgical blood order equation would result in a lower crossmatch-to-transfusion ratio than would the maximal standard blood order schedule (1.23 vs. 3.14). Costs were also lower with the surgical blood order equation.

CONCLUSION: Incorporation of patient factors resulted in increased efficiency of blood-ordering practices in total hip arthroplasty.