A. Q: What is deep vein thrombosis? A: Deep vein thrombosis (DVT) is a medical term used to refer to the formation of blood clots in the deep veins of the lower extremities, which can sometimes lead to life-threatening conditions. If a blood clot forms in a blood vessel, it can block the vessel, which can lead to obstruction of blood flow. When this happens in the deep veins of the lower extremities, stagnation of blood flow to the lower extremities occurs, leading to localized swelling and pain. On the other hand, when a venous thrombosis forms, the clot can circulate with the blood flow to other parts of the body, blocking the blood vessel in question. For example, when a blood clot forms in a lower extremity vein, it can travel with the bloodstream to the lungs, which can cause symptoms of respiratory distress. When the clot is large, it can lead to death. When a blood clot reaches the lungs with the circulation, it is called a “pulmonary embolism” or “PE”. Q: What are the symptoms of “DVT”? A: DVT can cause the following symptoms: swelling, pain, increased local skin temperature or redness of the skin, and sometimes a blood clot in a superficial vein near the surface of the skin, which is called “superficial vein thrombosis”. Superficial vein thrombosis can cause different symptoms, it can lead to more intense pain, localized redness of the skin and even infection. Superficial vein thrombosis can sometimes cause localized veins to stiffen and protrude from the skin, usually below the plane of the knee. If you suspect you have a deep vein thrombosis in a lower extremity, contact your doctor or nurse for help immediately. Superficial vein thrombosis is less dangerous, but deep vein thrombosis in the lower extremities is more dangerous. Your doctor or nurse will do the relevant tests to diagnose whether you have thrombosis, and if necessary, further treatment. Q: What are the symptoms of pulmonary embolism? A: Pulmonary embolism may cause the following symptoms: shortness of breath or dyspnea, sudden chest pain, coughing or hemoptysis aggravated by breathing movement, tachycardia. If you have any of these symptoms, especially if they occur within a short period of time (hours or days) or get worse quickly, call 120 immediately for help. At the hospital, your doctor will be able to check quickly to see if you have a blood clot. Pulmonary embolism can lead to death, so you need to act quickly to find out if you have a blood clot as soon as possible. Q: How should I treat deep vein thrombosis? A: The main treatment for DVT is to prevent the clot from further aggravating and reaching the lungs, including injectable medications and oral medications. Most patients with lower extremity DVT will first be treated in the hospital. Patients with DVT are usually given medications to prevent clots from forming, which are called “anticoagulants,” “blood-thinning drugs,” or “antithrombotics. Almost all patients are on oral anticoagulants for at least 3 months. Some patients receive subcutaneous “heparin” injections for several days, or for longer periods for those who cannot take oral anticoagulants. The role of anticoagulants is not to dissolve the clot that has formed, but to prevent further aggravation and formation of the clot. It is important to stay on anticoagulants for more than a few months because the body needs time to dissolve clots that have formed, and patients who have clots are at risk of having another clot in the first few months. When anticoagulants are not available or are not effective, there is another treatment option called “inferior vena cava filter” therapy. The inferior vena cava is the large blood vessel that returns blood from the lower extremities and the lower part of the body to the heart, and the filter is designed to stop and filter larger blood clots from reaching the heart. Bleeding, severe lower extremity deep vein thrombosis that can cause fatal pulmonary embolism, and in some cases, gangrene (disruption of blood supply to the lower extremities) due to the severity of the thrombosis. When this occurs, the physician may choose to apply a clot-dissolving drug. This is usually done by inserting a catheter into a deep vein and applying the thrombolytic drug locally. For some patients, the doctor may also choose to remove the clot surgically. Q: Are there ways to prevent thrombosis? A: Yes. Some patients develop venous thrombosis from sitting for too long. For example, people who travel long distances by air have a higher risk of thrombosis. When you fly for a long time, you can do the following measures to prevent the formation of blood clots: 1. stand up and walk after 1-2 hours of sitting still; 2. try not to smoke before the trip; 3. try to wear loose clothing; 4. move your position and move your lower limbs frequently when sitting; 5. drink as much water as possible; 6. wear stockings that are higher than your knees if possible; 7. avoid drinking alcohol and taking drugs for sleep because it will reduce your activity.