Most of the available evidence from two studies suggested that ASA results in fewer surgical site bleeds and is as effective as vitamin K agonists, low molecular weight heparin, or pentasaccharides for preventing venous thromboembolism after total hip arthroplasty, total knee arthroplasty, and hip fracture surgery. A prospective cohort study suggested that acetylsalicylic acid is less efficacious than low molecular weight heparin in reducing the risk of venous thromboembolism in standard-risk patients