Pulmonary embolism “downstream” usually refers to the placement of a vena cava filter for pulmonary thromboembolism, but not all pulmonary thromboembolisms require this type of treatment. Placement of an inferior vena cava filter may be considered in patients with definite pulmonary thromboembolism combined with deep vein thrombosis of the lower extremities, after careful evaluation by a physician for contraindications to anticoagulation. If pulmonary thromboembolism is combined with deep vein thrombosis of the upper extremities, an upper vena cava filter may be considered. Special attention should be paid to the fact that the primary role of the vena cava filter is to prevent the occurrence of pulmonary thromboembolism, and it should be used primarily in elderly, high-risk patients, with a definite presence of deep vein thrombosis or risk factors (e.g., being bedridden), with recurrent episodes of pulmonary thromboembolism, and with difficulty in tolerating anticoagulation therapy. For pulmonary thromboembolism that has already occurred, it is still necessary to actively treat under the guidance of a physician to develop the best diagnostic and therapeutic program according to different conditions.