Blood loss during primary total hip arthroplasty: use of preoperative measurements to predict the need for transfusion.

The blood loss resulting from total hip arthroplasty was studied in 53 patients. Calculated blood loss exceeded measured blood loss in all cases. The most significant predictor of postoperative packed-cell volume (PCV) was the preoperative PCV. In a further 37 patients the preoperative PCV was used successfully to predict the postoperative PCV and the need for transfusion.