First, venous thromboembolism is a chronic process that occurs acutely and requires sufficient time to restore the normal state of the coagulation waterfall, and therefore requires continued treatment outside the hospital; second, the bleeding side effects of anticoagulant drugs cannot be ignored and need to be monitored regularly; third, the occurrence of fatal pulmonary embolism may exist at any stage of thrombosis; the occurrence of post-thrombotic syndrome Fourth, post-hospital management and regular follow-up can not only ensure the accumulation of clinical data, but also increase the trust of patients in physicians.