This study examined the effect of pre-operative aspirin use on intra-operative bleeding and transfusion requirements in 242 patients undergoing thoracolumbar spinal fusion surgery. The patients were categorized based on their pre-operative aspirin use and their estimated blood loss, transfusion needs, and other demographic data were compared between these groups. The results showed no significant differences in estimated blood loss, transfusion requirements, or other outcomes between those who had and had not used aspirin pre-operatively. The study concluded that pre-operative aspirin use does not appear to increase intra-operative bleeding or transfusion needs for patients undergoing spinal fusion surgery.