Venous Thromboembolism

What is Venous Thromboembolism?

Venous thromboembolism is a condition where blood clots form inside your veins. These clots can partially or completely block blood flow. The term covers two related conditions that affect different parts of your body.

Deep vein thrombosis, or DVT, happens when a clot forms in a deep vein, usually in your leg or pelvis. Pulmonary embolism, or PE, occurs when a clot breaks free and travels to your lungs. A PE can block blood flow in your lungs and become life-threatening. About half of people with DVT have no symptoms at all.

Your body normally balances clotting and anti-clotting systems to keep blood flowing smoothly. When this balance tips too far toward clotting, venous thromboembolism can develop. Some people inherit genetic mutations that make their blood clot more easily than normal. Others develop clots due to temporary risk factors like surgery or long periods of sitting still.

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Symptoms

Swelling in one leg, ankle, or foot
Pain or tenderness in your leg that may feel like cramping
Warmth in the affected leg
Red or discolored skin on the leg
Sudden shortness of breath
Sharp chest pain that gets worse with deep breathing
Rapid heart rate
Coughing up blood
Lightheadedness or fainting

Many people with DVT have no noticeable symptoms, especially in the early stages. A pulmonary embolism can be the first sign that a clot has formed. This is why knowing your risk factors matters for prevention.

Causes and risk factors

Venous thromboembolism happens when blood flow slows down, the vein wall gets damaged, or your blood clots too easily. Sitting still for long periods during travel or bed rest slows blood flow in your legs. Surgery, injury, or certain medical procedures can damage vein walls. Inherited genetic mutations like Factor V Leiden or low Protein S levels make your blood more likely to form clots. Pregnancy, birth control pills, and hormone therapy also increase clotting risk.

Other risk factors include cancer and cancer treatments, being over age 60, obesity, smoking, and a personal or family history of blood clots. Certain autoimmune conditions and inflammatory diseases raise your risk as well. Having multiple risk factors at the same time significantly increases your chances of developing a clot. Understanding your individual risk helps you and your doctor make informed decisions about prevention.

How it's diagnosed

Doctors diagnose venous thromboembolism using imaging tests and blood work. An ultrasound can show blood clots in leg veins. A CT scan or special lung scan can detect clots in the lungs. Blood tests called D-dimer tests measure clot breakdown products and help rule out clots in some cases.

If you have had a blood clot or have a family history of clotting problems, your doctor may order specialized genetic and protein tests. These include tests for Factor V Leiden mutation and Protein S levels. Low free Protein S reduces your body's natural ability to prevent clots. The Factor V Leiden mutation makes your blood clot more easily than normal. Talk to your doctor about whether specialized clotting disorder testing is right for you.

Treatment options

Blood thinners, or anticoagulants, to prevent clots from growing and new clots from forming
Compression stockings to reduce swelling and prevent post-clot complications
Staying active and moving regularly to keep blood flowing through your veins
Elevating your legs when sitting or lying down to improve circulation
Drinking plenty of water to prevent dehydration and thick blood
Maintaining a healthy weight to reduce pressure on leg veins
Avoiding long periods of sitting still, especially during travel
Quitting smoking to improve overall vein and blood health
In severe cases, clot removal procedures or filters placed in large veins

Frequently asked questions

DVT is a blood clot in a deep vein, usually in your leg or pelvis. PE is when a clot breaks loose and travels to your lungs. Both conditions are types of venous thromboembolism. A PE often starts as a DVT that breaks free and moves through your bloodstream.

Small clots sometimes dissolve naturally, but you should never wait to see if this happens. Untreated blood clots can grow larger, break free, and travel to your lungs. This creates a life-threatening emergency. Always seek medical care immediately if you suspect a blood clot.

Factor V Leiden is a genetic mutation that makes your blood clot more easily than normal. People with this mutation have a higher risk of developing venous thromboembolism. About 5 out of every 100 people carry this mutation. Knowing you have it helps your doctor plan prevention strategies during high-risk times like surgery or pregnancy.

Protein S is part of your body's natural system that prevents blood clots from forming. When Protein S levels are low, this protective system doesn't work as well. Your blood becomes more likely to form clots when it shouldn't. Low Protein S can be inherited or develop due to certain medical conditions.

Testing makes sense if you've had a blood clot before age 50 without an obvious cause. You should also consider testing if multiple family members have had blood clots. Women who had clots during pregnancy or while taking birth control pills may benefit from testing. Talk to your doctor about your personal and family history to decide if testing is right for you.

Treatment length depends on what caused your clot and your ongoing risk factors. A first clot caused by temporary factors like surgery may need 3 to 6 months of treatment. Clots without a clear cause or those linked to genetic mutations may require longer treatment. Some people need lifelong blood thinners to prevent new clots.

Staying active helps keep blood flowing through your veins and reduces clot risk. Drink plenty of water, especially during travel or hot weather. Maintain a healthy weight and quit smoking. During long flights or car rides, stand up and walk every 1 to 2 hours. These lifestyle changes lower risk but may not be enough if you have genetic clotting disorders.

Birth control pills containing estrogen significantly increase clot risk in women with Factor V Leiden. This combination can raise your risk 30 to 50 times higher than normal. Talk to your doctor about non-estrogen birth control options. Progestin-only pills, IUDs, and barrier methods are safer alternatives.

A pulmonary embolism blocks blood flow in your lungs, making it hard to breathe. You may feel sudden chest pain, rapid heartbeat, or cough up blood. Large clots can prevent your lungs from delivering oxygen to your body. This is a medical emergency that requires immediate hospital treatment with blood thinners or clot removal procedures.

Yes, about 3 out of 10 people who have one clot will develop another within 10 years. Your risk of recurrence is higher if you have genetic clotting disorders or ongoing risk factors. People with unprovoked clots, meaning no clear trigger, face higher recurrence rates. Your doctor may recommend longer blood thinner treatment or lifestyle changes to reduce this risk.