What Is Deep Vein Thrombosis?

Deep vein thrombosis (DVT) is a blood clot that partially or completely blocks a large vein (usually in the lower leg or thigh, like the popliteal vein) though it can occur in other parts of the body.

If that blood clot breaks off, it becomes an embolus and can travel through the heart and lungs, blocking passage for blood flow there. A blood clot that travels to your lungs is called pulmonary embolism (PE). PE can deprive the tissues of blood and damage tissues. DVT is very serious and can be fatal.

According to the National Heart, Lung and Blood Institute, blood clots in the thighs are more likely to break off and cause PE than blood clots in the lower leg.

It's important to note that DVT is different from a blood clot (also known as superficial thrombophlebitis), which forms in the veins just beneath the skin. Superficial thrombophlebitis doesn't usually travel to the lungs and can be treated with anti-inflammatory medications, bed rest, and warm compresses. DVTs are also different from blood clots that occur in the arteries, which can lead to a heart attack or stroke. 

Deep Vein Thrombosis Symptoms

Common symptoms of DVT are pain and tenderness in the affected area, and redness or discoloration of the skin. If the DVT breaks off and becomes a PE, you may experience chest pain, rapid heartbeat, and difficulty breathing. Vomiting, coughing up blood, and fainting are also signs of a PE.

DVT and PE are serious, so if you have any of these signs or symptoms, seek help immediately.

Causes

One of the biggest causes of DVT is being immobile and sitting for extended periods of time. Whether you're recovering from surgery or sitting on a long flight, being inactive slows the blood flow and can prevent the platelets and plasma in your blood from mixing and circulating properly.

Having a major injury or surgery in the leg can also cause DVT.

Diagnosis

If you have a DVT, it's important to get diagnosed right away before it becomes a pulmonary embolism. Once a PE blocks an artery in your lung, all blood flow is reduced or stopped completely, which can cause sudden death.

Your healthcare provider will most likely perform a compression ultrasound, but other tests, like a venogram, CT scan, or D-dimer test, can also be used to diagnose DVT. Through a compression ultrasound, your practitioner is able to see the blood clot and the obstruction of blood flow in the vein. 

Treatment

If your healthcare provider confirms a DVT diagnosis, the first line of treatment is usually anticoagulants (blood thinners). Anticoagulants do not break up existing clots, but work to prevent further blood clotting in the veins and reduce your chances of developing a PE. There are injectable and pill forms of anticoagulants.

If you do develop a PE and have a large clot, you may be prescribed thrombolytic therapy (clot-busting medication). These medications are given through IV or a catheter injected directly into the clot. Clot busting medications are typically reserved for emergency cases due to the risk for severe bleeding.

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Once short-term treatment is done, your healthcare provider may put you on another anticoagulant. Anticoagulation therapy usually continues for three months, but in some cases, it can be indefinite, especially if you've had a PE. Your practitioner will evaluate your case against the risks and benefits as part of their clinical decision-making.

Prevention

It's important for people at risk of DVT, or those who have had one, to maintain a healthy lifestyle. Quitting smoking, achieving a healthy weight, and following a regular exercise routine are all helpful prevention strategies.

You should avoid sitting for long periods of time and stretch and move throughout the day. Compression socks are especially helpful on long flights because they aid in circulation and help the leg veins return deoxygenated blood to the heart.

If you're taking birth control or hormone replacement therapy, you can talk to your healthcare provider about changing your treatment plan to prevent future clots. People who have hypertension, heart disease, or heart failure are also at a high risk of DVT, so be sure to talk with your healthcare provider about creating a treatment plan that lowers your risk and prevents clots.

A Word From Verywell

Deep vein thrombosis is a serious condition that should be treated immediately. It usually takes three to six months for the clot to completely resolve, but through medical treatment, you can prevent the clot from increasing in size and breaking away.

If you experience symptoms of pulmonary embolism, get help right away. While the symptoms of DVT can be alarming, knowing them can help save your life or someone you know.