After being diagnosed with deep vein thrombosis in the hospital, many patients are faced with many doubts: Is this disease serious or not? How to treat it? What are the after-effects? Is the treatment given to me by the hospital where I live appropriate? Here, we would like to introduce the basic knowledge of deep vein thrombosis and standardized treatment to the patients systematically. 1.What is deep vein thrombosis? What is the danger? Deep vein thrombosis refers to the abnormal clotting of blood in the deep veins. After the formation of thrombosis, except for a few that can ablate on their own or be confined to the site of occurrence, if left untreated, most of them will spread to the deep vein trunk of the whole limb and even complicate pulmonary embolism, causing extremely serious consequences. If not diagnosed and treated in time, about half of the cases will evolve into post-thrombotic syndrome, which will affect the quality of life of patients for a long time and make them incapable of working. 2.How to treat after deep vein thrombosis? The treatment after deep vein thrombosis is divided into acute, subacute and chronic phases, and the most basic treatment at present is anticoagulation. The duration of anticoagulation treatment depends on the specific situation. For the unknown cause of thrombosis, anticoagulation treatment is at least 6 months; for the clear cause of thrombosis, such as trauma or fracture, anticoagulation treatment is 3 months; if there is easy embolism, long-term anticoagulation is recommended. Because of the risk of dislodgment of the thrombus leading to fatal pulmonary embolism, there are some cases where the placement of an inferior vena cava filter should be considered, depending on whether there is an indication for filter placement. The filter is placed into the vena cava, which is the pathway between the limb vein and the pulmonary artery, to intercept the thrombus and prevent a fatal pulmonary embolism if it dislodges. Indications include: 1) contraindication to anticoagulation or thrombolysis; 2) progression of thrombus or pulmonary embolism at the same time of regular anticoagulation; 3) high position of thrombus or “floating” thrombus; 4) intraoperative or postoperative prevention of pulmonary embolism in preparation for the procedure of thrombus extraction or placement of thrombolysis. The above indications are not absolute, but can be used as a reference. If the onset time is short (within 14 days), direct catheter thrombolysis can be tried, that is, the catheter is inserted directly into the thrombus for thrombolysis, which can effectively reduce the occurrence of “post-thrombotic syndrome”. The incidence of “post-thrombotic syndrome” can be as high as 30-50% or more if the treatment is improper, which is characterized by repeated swelling, pain, limb pigmentation, and even skin ulceration, venous claudication, etc., which seriously affects the quality of life and even loss of working ability. If the thrombosis occurs in a short period of time and the symptoms are severe, such as white swelling of the femur or bruising of the femur, incision and embolization treatment can also be chosen, but it is not routinely used at present.