A comparison between rivaroxaban and placebo for the prevention of deep vein thrombosis or pulmonary embolism afetr laparoscpic surgery for colorectal cancer after initial heparin prophylaxis

Primary objectives: To assess the efficacy and safety of postdischarge extended (3 weeks) antithrombotic prophylaxis with rivaroxaban compared to placebo after planned laparoscopic surgery for colorectal cancer in patients who had received antithrombotic prophylaxis with LMWH during the hospital stay for 7±2 days
Primary endpoints: The primary study outcome is a composite of symptomatic objectively confirmed VTE, asymptomatic ultrasonography-confirmed DVT or VTE-related death at 28±2 days from planned laparoscopic surgery for colorectal cancer in patients randomized to rivaroxaban or placebo.Pulmonary embolism will be diagnosed in the presence of:- intraluminal filling defect at computed tomography angiography or pulmonary angiography- high probability perfusion defect at perfusion lung scan with mismatch area compared to chest X Ray.Deep vein thrombosis will be diagnosed in the presence of:- an uncompressible vein segment in the deep vein of the lower limbs as assessed by complete compression ultrasonography examination