Deep vein thrombosis, or DVT, is a blood clot in a deep vein, most often in the leg. On its own it can cause pain and swelling, but the bigger danger is that part of the clot can break off and travel to the lungs, causing a pulmonary embolism (PE), which can be life-threatening. Together these conditions are known as venous thromboembolism (VTE), and they affect hundreds of thousands of Americans every year. Knowing the signs and the risk situations can save lives.
Symptoms of DVT
DVT usually affects one leg. Symptoms can include:
- Swelling of the calf, ankle or whole leg
- Pain or tenderness, often starting in the calf and feeling like a cramp or soreness
- Warmth in the affected area
- Red or discolored skin
- Enlarged veins near the surface
About half of people with DVT have no clear symptoms at all.
Warning signs of a pulmonary embolism
Call 911 immediately if you have:
- Sudden shortness of breath
- Sharp chest pain that is worse when you breathe in or cough
- A fast heartbeat
- Coughing up blood
- Feeling light-headed, dizzy or fainting
A pulmonary embolism can happen even if you never noticed leg symptoms.
Who is at risk
Clots form when blood flow slows, the blood becomes more likely to clot, or a vein wall is injured. Common risk factors include:
- Surgery, especially hip or knee replacement and major abdominal or cancer surgery
- Hospital stays and long periods of bed rest
- Long journeys of four hours or more by plane, car or train
- Cancer and some cancer treatments
- Pregnancy and the first six weeks after giving birth
- Estrogen-containing birth control pills and hormone therapy
- Injury, such as a broken leg
- Obesity
- Smoking
- Older age, especially over 60
- A personal or family history of blood clots
- Inherited clotting conditions, such as factor V Leiden
- Heart failure, inflammatory bowel disease and some autoimmune conditions
How DVT is diagnosed
- Clinical assessment using a scoring system (the Wells score) to estimate how likely a clot is
- D-dimer blood test: a normal result in a low-risk person makes a clot unlikely, but a high result is not specific and needs further testing
- Compression ultrasound of the leg veins, the main test to confirm DVT
- CT pulmonary angiography if a pulmonary embolism is suspected
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Treatment
Anticoagulants
The main treatment is anticoagulant medicine, often called a blood thinner. These do not dissolve the existing clot but stop it from growing and prevent new clots while the body gradually breaks it down.
- Direct oral anticoagulants (DOACs) such as apixaban and rivaroxaban are now used most often. They work quickly and do not need routine blood tests.
- Low molecular weight heparin injections are preferred in some situations, such as pregnancy and some cancers.
- Warfarin is still used for certain patients, such as those with mechanical heart valves, and requires regular INR blood tests.
Most people take anticoagulants for at least three months. If the clot had no clear trigger or keeps coming back, treatment may be continued long term.
Blood thinners raise the risk of bleeding. Seek urgent help for black or bloody stools, vomiting blood, blood in urine, severe headache or a serious fall.
Other treatments
- Clot-dissolving medicine or catheter procedures for large, life-threatening pulmonary embolisms or extensive leg clots
- IVC filters, small devices placed in a large vein to catch clots, used only when anticoagulants cannot be taken
- Walking is usually encouraged once treatment starts, as it helps symptoms
Post-thrombotic syndrome
Some people develop long-term leg swelling, pain, heaviness and skin changes after a DVT, called post-thrombotic syndrome. Staying active, keeping weight healthy and, for some, wearing compression stockings can help manage symptoms.
Preventing blood clots
Around surgery and hospital stays: ask your care team about your clot risk. Many patients receive preventive anticoagulants, compression devices, or both. Get up and walk as soon as you safely can.
On long trips:
- Get up and walk every one to two hours when possible
- Flex and point your feet and do calf exercises while seated
- Stay hydrated and limit alcohol
- Choose an aisle seat if you can
- If you are at higher risk, ask your doctor about properly fitted compression stockings
Every day:
- Stay active and maintain a healthy weight
- Stop smoking
- Discuss clot risk with your doctor before starting estrogen-containing birth control or hormone therapy, especially if you have a personal or family history of clots
The bottom line
A swollen, painful, warm leg can be a sign of a blood clot and needs prompt medical assessment. Sudden breathlessness or chest pain could be a pulmonary embolism, so call 911. Blood clots are treatable with anticoagulants, and many can be prevented by staying mobile, especially after surgery and on long journeys.
This article is for general information and does not replace medical advice.