Post-operative retransfusion of unwashed filtered shed blood reduces allogenic blood demand in hip hemiarthroplasty in traumatic femoral neck fractures-a prospective randomized trial

229 patients scheduled for hemiarthroplasty following a femoral neck fracture were randomized to postoperative use of either an autologous blood transfusion system or standard closed suction drainage. Autologous blood transfusion systems were set to retransfusion if a minimum of 100mL of blood was collected within the first 6 hours after surgery. Overall, the difference between groups in the mean number of allogenic red blood cell units transfused postoperatively was not significant. Only approximately one-third of patients in the ABT group had enough blood loss in the first 6 hours postoperative to trigger autologous retransfusion.