Determination of lower extremity vascular blockage needs to be based on whether the patient has factors that cause lower extremity thrombosis, clinical manifestations, imaging examinations and other comprehensive analysis. 1. Causes: Thrombosis in the lower limbs of the organism is most common in patients who have undergone major surgery, severe trauma, long-term bedridden patients, patients with limb braking and patients with malignant tumors, which mainly causes slow blood flow, endothelial damage, blood coagulation and the formation of thrombus caused by vascular blockage in the lower limbs. 2. Clinical manifestations: Usually, patients can have sudden swelling of the affected limbs, and in the acute stage, the skin color can be red, and the skin temperature is higher than that of the healthy limbs, and at the same time, there is persistent pain, pressure and pain, distension and pain, etc. If the dislodgement of the clots reaches the lungs along with the blood flow, it can cause hemoptysis, chest pain, respiratory difficulties and other symptoms. 3. Imaging: For example, color Doppler ultrasound can determine whether thrombus exists in the deep veins of the lower limbs, as well as the location and scope of the thrombus; lower limb venography can most directly show the morphology of the veins, which is the gold standard for the diagnosis of deep vein thrombosis of the lower limbs. It is recommended to consult the doctor as soon as possible to avoid delaying the condition.