If you work sedentary for a long time, overweight, and have unexplained lower limb swelling, pain, and superficial varicose veins, beware – lower limb vein thrombosis is looking for you. The blood of human body starts from the heart, is transported to the lower limbs through the arterial system, and then flows back to the heart through the venous system, which is the longest journey. If the calf muscles are in a relaxed state at this time, the veins of the lower limbs are relatively easy to form thrombosis in the same state in all parts of the body. The most dangerous consequence of lower limb vein thrombosis is – pulmonary embolism, often heard of “economy class syndrome” refers to: long time flying, sitting in a narrow space can not move, the lower limb vein blood flow is slow, stagnation and the formation of lower limb deep vein thrombosis. After getting off the plane, the thrombus is dislodged when the activity occurs, with the blood flowing back to the right heart, then into the pulmonary artery causing embolism, making the lungs ischemia, hypoxia, causing chest pain, shortness of breath, hemoptysis and other symptoms, which can cause sudden death in serious cases. In addition, there are also reports of sudden death due to pulmonary embolism after prolonged sitting in trains, automobiles, white-collar workers who work in front of computers for a long time, and some young people who are addicted to computer games or the Internet. Venous thrombosis of the lower limbs can be treated, and the key is to be vigilant, and to seek medical attention promptly after discovering unexplained swelling, pain and varicose veins in the lower limbs, and to avoid the serious consequence of pulmonary embolism if deep vein thrombosis can be detected and treated early. According to our experience, the most common symptom is lower limb swelling, and the first department is usually internal medicine or emergency department, because heart, kidney, and lower limb infection may cause it, but the lower limb swelling caused by these diseases is mostly bilateral, and unilateral lower limb swelling, while the superficial veins are thickened and tortuous than the opposite side, should be more considered as venous thrombosis, and should be seen in the interventional clinic. By analyzing the medical history and the results of the examination, if deep vein thrombosis is suspected, blood may be drawn for D-dimer and color ultrasound and CT examination of the blood vessels of the lower limbs are done. After the diagnosis is confirmed, the next treatment is mainly done by the interventional department. It includes three aspects: first, drug injection to stop the thrombus from continuing to increase in size or even dissolve the thrombus already produced; second, to prevent the thrombus from dislodging into the pulmonary artery by implanting a temporary or permanent inferior vena cava filter; third, to prevent the thrombus from occurring again in the future, i.e., to continue to take the oral anticoagulant Favarin for a period of time or even for life after discharge from the hospital. Pulmonary embolism is scary, yet preventing it is simple and effective. For urban humans who are sedentary for long periods of time, all we need to do is to move more and drink more water. So the next time you sit for two hours straight, remember to get up and take a few steps, stir your legs, and keep your deep veins open.