COLLAGEN-INDUCED WHOLE-BLOOD PLATELET-AGGREGATION IN PATIENTS UNDERGOING SURGICAL-PROCEDURES ASSOCIATED WITH MINIMAL TO MODERATE BLOOD-LOSS

wIntraoperative bleeding due to platelet disorders is a persistent pro blem. Therefore, a screening assay to identify patients who are likely to bleed as a result of platelet dysfunction would be useful in formu lating decisions about patient care. A previous study indicated that p reoperative collagen-induced whole blood platelet aggregation predicts bleeding in patients undergoing surgery with cardiopulmonary bypass, a procedure associated with substantial blood loss. In the current stu dy we assessed the ability of the same whole blood platelet aggregatio n test to predict blood loss in patients undergoing surgical procedure s not associated with substantial blood loss. The study included 369 a dult patients (165 men and 204 women). Patients were categorized in th ree groups depending on the invasiveness of the operation and the expe cted blood loss. The intraoperative estimated blood loss value, obtain ed from the operative report in the patient record, increased signific antly with increasing surgical invasiveness. Patients with excessive b lood loss (defined as blood loss at or above the 75th or 90th percenti le of the estimated blood loss values of patients undergoing procedure s of similar invasiveness) had similar platelet aggregation values as patients who did not experience excessive blood loss. Thus, for patien ts undergoing operations not associated with substantial blood loss, t he results of preoperative collagen-induced whole blood platelet aggre gation are not effective in identifying patients likely to experience excessive blood loss.