Acute lower extremity deep vein thrombosis is a common condition in vascular surgery. Patients who are not treated promptly may suffer from pulmonary embolism due to dislodged thrombus. The dislodged fresh thrombus mainly originates from the deep veins of the lower extremities. What is pulmonary embolism? What are the dangers? Pulmonary embolism refers to a series of clinical and pathophysiological syndromes such as blockage of pulmonary artery or its branches by dislodged thrombus, resulting in obstruction of pulmonary circulation in patients. According to the epidemiological data in Europe and America, the incidence of pulmonary embolism caused by the dislodgement of deep vein thrombus in the lower extremities accounts for about 60%-70%, and it has also been reported that the death rate of pulmonary embolism can be as high as 20%-30%. When pulmonary artery embolism occurs, the clinical manifestations of the lighter cases are dyspnea, chest tightness, chest pain, syncope, hemoptysis, irritability, and even sudden cardiac and respiratory arrest and death. Pulmonary embolism is not rare in China, and its incidence has been increasing in recent years. Thus, it can be seen that pulmonary embolism is critical and rapid, and its main danger is thrombus dislodgement, and the prognosis is very poor if not treated timely. Can pulmonary artery embolism be prevented? How to avoid pulmonary embolism after the occurrence of lower extremity deep vein thrombosis? What reliable treatment measures are available for this disease? Due to the lack of common sense understanding of the disease among patients and their families, it is difficult to make up their mind about the active prevention program of pulmonary embolism proposed by hospitals, and even individual non-specialized medical personnel also lack the knowledge of the disease. Therefore, it is necessary to carry out the popularization of relevant medical and health knowledge. In recent years, with the continuous development of new medical equipment, there have been new advances in early diagnosis and especially early prevention of pulmonary artery embolism. At present, the most effective method recommended to prevent pulmonary embolism is the placement of an inferior vena cava filter into the patient by interventional procedures. It should be noted that filters have no therapeutic effect on deep vein thrombosis, so why do doctors recommend early placement of filters? It should be explained from the design principle that a venous filter is like a screen, which is like an open umbrella in the patient’s blood vessels; a thrombus is like a time bomb that can explode at any time in the patient’s body. Patients with lower limb DVT, especially during the acute phase or thrombolysis and anticoagulation treatment, may have the thrombus in the DVT system suddenly dislodge and block the pulmonary artery due to deep breathing, violent coughing, defecation, body position movement and squeezing the affected limb. The important role of the filter is to effectively intercept the thrombus on its way to dislodge, thus preventing pulmonary embolism and significantly reducing the incidence of pulmonary artery embolism. Is it safe to place a vena cava filter? The inferior vena cava filter placement procedure is generally safe, reliable, easy to perform, and minimally invasive, but no procedure is absolutely safe. There are serious complications associated with filter insertion, such as displacement, tilting, obstruction, inferior vena cava perforation, and bleeding. In the event of such postoperative complications, patients must be seen by a vascular surgeon for specialized management. How to reduce the complications of inferior vena cava filter placement? The following 3 points should be noted: 1. Clinical indications for inferior vena cava filter placement should be strictly controlled. 2. The procedure should be performed in a specialty with relevant interventional equipment. 3.Postoperatively, the doctor needs to properly guide the patient with systematic anticoagulation therapy and follow-up. In conclusion, the patient’s treatment plan should be determined by weighing the pros and cons according to the needs of the condition, and the treatment should not be based on the pursuit of a new technology, nor should it be regretted for the delayed and missed opportunity.