Aspirin usage and perioperative blood loss in patients undergoing unexpected operations.

The effect of aspirin on perioperative blood loss was studied in 52 patients undergoing unplanned operation. Twenty-two of 52 patients were found to have taken aspirin prior to operation. Five others were suspected of having taken aspirin or some aspirin-like drug prior to operation. All patients who remembered taking aspirin preoperatively had significantly decreased platelet thromboxane B2 levels caused by aspirin inhibition of platelet arachidonic acid metabolism. Eight of 22 patients who took aspirin had abnormal template bleeding times. No significant increase occurred in the perioperative blood loss of patients who had taken aspirin. Neither the aspirin induced decrease in thromboxane B2 levels nor the increase in template bleeding times was associated with an increased perioperative blood loss. We concluded that aspirin is commonly used prior to unplanned operations but that preoperative aspirin usage does not result in increased perioperative blood loss in patients with normal platelet counts and with normal coagulation factors. These results suggest that there is no need to delay operation in this group of patients because of recent aspirin ingestion.