A venous thromboembolism is a blood clot that blocks the flow of blood through your veins. A VTE can be stuck in the deep veins of the legs or arms (deep vein thrombosis) or travel through the veins to the lungs (pulmonary embolism). A VTE that blocks the lungs is life-threatening.
A venous thromboembolism is a blood clot that blocks the flow of blood. "Thrombo" means blood clot, and "embolism," means a circulating particle that causes an obstruction. "Venous" means in the veins. When healthcare providers talk about venous thromboembolism (VTE), they often talk about it as a disorder that can lead to two different kinds of blood clotting conditions: deep vein thrombosis and pulmonary embolism.
Veins carry blood from the extremities of your body back to your heart. When a vein is blocked, blood pools behind the blockage, causing inflammation, and cells ahead of the blockage can’t get the oxygen and nutrients they need. This can do serious damage to the veins, tissues and organs that they feed. In some cases — such as when a VTE blocks blood flow to the lungs — it can be life-threatening.
Blood clotting is a normal and healthy response to a superficial cut or wound. Your blood coagulates — partially solidifies — in order to keep it from leaking too fast from a hole. On the outside of your body, this produces a scab. On the inside of your body, it produces a clot. Blood clotting can also be triggered by an infection, which irritates the lining of the blood vessel like a wound. When the wound or infection begins to heal, the clot is supposed to dissolve. But sometimes it doesn’t. And sometimes blood clots form when there was no wound. Many factors can contribute to this. If the clot is big enough, it can block the vein.
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A venous thromboembolism is not the type of blood clot that typically causes a heart attack or stroke. Those are usually caused by blood clots in your arteries, not in your veins. But a VTE can be just as dangerous. The most serious complications occur when a VTE breaks loose from where it formed, travels through your bloodstream, and gets stuck in the veins of your lungs. This is called a pulmonary embolism (PE). A PE restricts oxygen and blood flow to your lungs while increasing blood pressure in your arteries. This causes pulmonary hypertension, which in turn can cause heart failure and death.
VTEs usually form in the deeper veins of your body, embedded in the muscles of your legs or arms. When a blood clot is stuck in your deeper veins, it’s called a deep vein thrombosis (DVT). A DVT that blocks the vein causes inflammation at the site of the blockage and can cause long-term damage to the vein, resulting in chronic venous insufficiency (post-thrombotic syndrome). Not all DVTs cause an obstruction, but because they can, they are considered a venous thromboembolic disease. DVTs can also break loose and travel to your lungs, leading to pulmonary embolism (PE).
A thrombosis is a blood clot. A thromboembolism is a circulating blood clot that gets stuck and causes an obstruction. Both deep vein thrombosis and pulmonary embolism are included under the umbrella term of venous thromboembolic diseases because both have the potential to obstruct blood flow in your veins. Blood clots that occur in the smaller, superficial veins close to your skin (superficial venous thrombosis) don't tend to cause the same kinds of complications. About half of DVTs don’t cause complications either, but they can, and they remain a risk factor for PE.
In the U.S., VTE is the third most common vascular diagnosis after heart attack and stroke. It affects about 1 in 1,000 Americans each year. About half of people with VTE experience a pulmonary embolism. About 25% of those who have a pulmonary embolism die from it. After the age of 40, your risk of VTE almost doubles every decade.
Anyone can get a VTE, but certain factors put you more at risk. About 25% to 50% of cases arise without obvious cause. Another 20% are associated with cancer, and 20% with surgery. Some people also have blood clotting disorders that make them more prone to clots.
Blood clots can occur for many reasons, and no one factor makes them more likely to be big enough to obstruct a vein, or to break loose and travel to your lungs. Anyone who is at risk of blood clotting is at risk of venous thromboembolism. And anyone who is at risk of a VTE is at risk of a pulmonary embolism. People who develop VTEs often have more than one risk factor contributing to the condition.
Some people have an imbalance of blood-clotting proteins, which makes their blood more prone to clot and less prone to dissolve clots (thrombophilia). This can be inherited, or it can be a side effect of a specific condition. Sometimes a lack of movement causes your blood to slow down too much in your veins and it starts to coagulate. This can come from long-distance travel or a sedentary lifestyle.
The most natural cause of blood clotting is injury or infection. Sometimes the injury comes from a medical intervention, like surgery or chemotherapy or inserting an IV or catheter. People who are in the hospital for a long time are more at risk of clotting, because they may be healing from a wound or infection and also subject to invasive medical interventions, and also immobilized in a hospital bed.
Signs of an obstructive DVT occur at the site of the clot. They can include:
Signs of a PE may occur without any previous signs of DVT. They can include:
Other conditions can have similar symptoms to DVT and PE. To confirm that you have a venous thromboembolic disease, your healthcare provider will ask about your medical history to identify risk factors of VTE and rule out other possible conditions. They might take a preliminary blood test to look for markers of blood clotting. Then they will use imaging tests to try and locate the blockage.
Different tests are used to diagnose DVT and PE.
Venous thromboembolism treatment options vary depending on how threatening the clot is. Some DVTs may be managed with oral medications, while some PEs may need to be urgently removed. Your healthcare provider might remove a life-threatening PE through a catheter in your vein, or they might inject a medication called a thrombolytic that dissolves the clot quickly. Because of possible complications, though, these interventions are reserved for emergencies.
When a VTE is not immediately life-threatening, treatment focuses on preventing existing clots from getting bigger and new clots from forming. Preventative treatments include anticoagulants (blood thinners) that reduce clotting and compression stockings that encourage circulation. For trickier cases, your healthcare provider might suggest a physical intervention, such as installing a filter in the vein to keep clots from reaching the lungs.
Venous thromboembolism has many risk factors, and not all of them can be managed. But in general, movement is the easiest prevention. Since most DVTs occur in the legs, you can mitigate a lot of risk by keeping blood circulating in your legs. If you sit a lot for work or travel, make sure to get up and walk or exercise your leg muscles periodically to keep blood from pooling. If you’ve been sick or you’re recovering from surgery, getting up and moving as soon as you can will help reduce the risk of clots. Exercise will also help you keep stress levels down and maintain a healthy weight, which are other contributing factors.
A note from Cleveland Clinic
So many different things can contribute to a venous thromboembolism. You may have risk factors that you weren’t aware of or that you can’t change. However, there’s a lot you can do to prevent a VTE, and manage it effectively if it does occur. If you’re concerned, talk to your healthcare provider about your particular risk factors and how to mitigate your risk. If you do notice symptoms of a VTE, seek medical care right away. We take all blood clots seriously, the ones you have now and the ones you may have.
Last reviewed by a Cleveland Clinic medical professional on 02/22/2022.
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