Patient: The old man is 66 years old and has lower extremity vein thrombosis ultrasound test results as attached local hospital doctor said that there is no way to operate. What are the risks of surgery? Will there be any sequelae or complications? If surgery is not performed, what are the possible conditions? Is it likely to continue to get worse? If no surgery, how will it be treated? Are there any supportive devices that are effective? The diagnosis of lower extremity DVT is clear based on the ultrasound results. The surgical treatment of lower extremity DVT can be divided into two categories, one is the incision of veins to remove embolism and the other is the implantation of inferior vena cava filter. Surgery is not the principle of treatment of lower extremity DVT, and the current unified view in China is that it is the absolute indication of thrombectomy only when the lower extremity DVT forms white swelling of femur or bruise of femur, which endangers the survival of the limb. The purpose of inferior vena cava filter implantation is to prevent pulmonary infarction due to dislodgement of DVT, but it has no benefit for the treatment of DVT of lower extremity itself. The principles of treatment for lower extremity DVT include anticoagulation, thrombolysis, improvement of microcirculation, and limb compression therapy. Anticoagulation is the most important treatment measure, and thrombolysis can be considered during the acute period; after the acute period, thrombolysis is not too necessary. In addition, treatment can be combined with compression stockings and intermittent pneumatic compression devices. The most serious complication of lower extremity DVT is the dislodgement of the thrombus into the pulmonary artery leading to pulmonary infarction, which can be fatal and is generally considered necessary if pulmonary infarction is highly suspected or diagnosed, or if there are contraindications to anticoagulation. In fact, the vast majority of patients with lower extremity DVT can achieve significant improvement in their symptoms after treatment with anticoagulation, thrombolysis, improvement of microcirculation, and limb compression therapy.