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Other Names:
DVT, Venous thrombosis, Blood clot in the legs
Deep Vein Thrombosis

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What Is Deep Vein Thrombosis?

A deep vein thrombosis (throm-BO-sis) is a blood clot that forms in a vein deep in the body. Most deep vein clots occur in the leg or hip veins. They also can occur in other parts of the body. Blood clots in the veins in the thigh are usually more serious than blood clots that happen in veins in your lower leg. If a clot in a vein breaks off and travels through your bloodstream, it can lodge in your lung. This is called a pulmonary embolism, which is a very serious condition that can cause death. Blood clots also can occur in veins that are close to the surface of the skin. These types of blood clots are called superficial venous thrombosis or phlebitis (fle-BI-tis). Blood clots in superficial veins cannot travel to the lungs.

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What Makes Deep Vein Thrombosis More Likely?

There are many factors that may increase your risk for deep vein clots.
  • An inherited condition that causes increased risk for clotting
  • Low blood flow in a deep vein, due to injury, surgery, or immobilization
  • Cancer and its treatment
  • Other medical conditions such as varicose veins
  • Sitting for a long period of time like on a long trips in a car or on an airplane
  • Pregnancy, especially the first 6 weeks after giving birth
  • Being over age 60 (although deep vein thrombosis can occur in any age group)
  • Being overweight
  • Taking birth control pills or hormone therapy, including for postmenopausal symptoms
  • Central venous catheters now account for almost 1 in 10 cases.
Your risk for deep vein clots increases if you have several risk factors at the same time. For example, a woman with an inherited condition for clotting who also takes birth control pills has an even higher risk to have a blood clot.

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What Are the Signs and Symptoms of Deep Vein Thrombosis and of Pulmonary Embolism?

Only about half of the people with deep vein thrombosis have symptoms. The symptoms may include:

Deep vein thrombosis
  • Swelling of the leg
  • Pain or tenderness in the leg-the pain is usually in one leg and may only be present when standing or walking
  • Feeling of increased warmth in the area of the leg that is swollen or that hurts
  • Red or discolored skin.
Pulmonary embolism
  • Chest pain when you take a deep breath
  • Shortness of breath.
Some people only find out they have a deep vein thrombosis after the clot has moved from the leg and traveled to the lung (pulmonary embolism). It is important to see a doctor right away if you have symptoms of a pulmonary embolism or deep vein thrombosis.

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How is Deep Vein Thrombosis Diagnosed?

Your doctor will obtain a medical history and examine you to determine if you have deep vein thrombosis.

Duplex ultrasound is the most common test used to diagnose deep vein clots. It uses sound waves to evaluate the flow of blood in your veins. A gel is put on the skin of the leg. A handheld device is placed on the leg and passed back and forth over the affected area. This device sends sound waves from the leg to an ultrasound machine. A computer then turns the sounds into a picture. The picture is displayed on a TV screen where your doctor can see the blood flow in your leg.

Venography may be performed if the Duplex ultrasound does not provide a clear diagnosis. A venogram is an x-ray used to examine veins. A dye is injected into a vein and then an x-ray is taken of the leg. The dye makes the vein visible on the x-ray. If the blood flow in the vein is slowed, it will show on the x-ray.

Less frequently used tests

  • Magnetic Resonance Imaging (MRI) shows pictures of organs and structures inside the body. MRI uses radio waves to make the image. In many cases, MRI can provide information that would not show up on an x-ray. This test is being used more frequently to diagnose deep vein thrombosis.
  • Computed tomography (CT) scan is a special type of x-ray that can provide pictures of structures inside the body. This test is rarely used to diagnose deep vein thrombosis.
If your doctor suspects that an inherited disorder could be causing the clots, the doctor may test for these disorders. This may be important if:
  • You have repeated blood clots that cannot be linked to any other cause
  • You have a blood clot in a vein at an unusual location, such as a vein from the liver, kidney, or brain.

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How Can I Prevent Deep Vein Thrombosis?

Preventing deep vein thrombosis depends on whether you have had a clot before or if you are at risk for developing a deep vein clot but never had one. If you have had a deep vein clot, then you will need to prevent further clots from developing by:
  • Taking your medications to prevent or treat blood clots as prescribed by your doctor
  • Following up with your doctor for medication changes and blood work.
If you have never had a deep vein clot, but are in a situation that may increase your risk, be sure to:
  • Exercise your lower leg muscles if you will be sitting still for long periods of time.
  • Get out of bed and move around as soon as you are able after having surgery or being ill. The sooner you move around the less chance you have to develop a clot.
  • Take medications to prevent clots after some types of surgery as directed by your doctor.
  • Follow up with your doctor.

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How is Deep Vein Thrombosis Treated?

The main goals in treating deep vein thrombosis are to:
  • Stop the clot from getting bigger
  • Prevent the clot from breaking off in your vein and moving to your lungs
  • Reduce your chance of having another blood clot.
There are several medications used to treat and/or prevent deep vein thrombosis:

Anticoagulants (sometimes called blood thinners) decrease your blood's ability to clot. They are used to stop clots from getting bigger and to prevent a blood clot from forming. Anticoagulants do not break up blood clots that have already formed. Your body's natural system will dissolve the clot. Anticoagulants can either come as a pill (warfarin) or as an injection or shot (heparin).

Heparin and warfarin may be given at the same time. Heparin will act quickly, while the warfarin will take 2 to 3 days before it starts to work. Once the warfarin is working, the heparin will be stopped. Pregnant women cannot take warfarin and will be treated with heparin only.

Treatment for deep vein thrombosis with anticoagulants usually lasts for 3 to 6 months. However, the following situations may change the length of treatment:
  • If your blood clot occurred after a short-term risk like surgery, your treatment may be shorter
  • If you have had clots before, you will need longer treatment
  • If you have another illness (like cancer) you are being treated for, you will take anticoagulants for as long as those risk factors are present.
The most common side effect of anticoagulants is bleeding. Blood tests will check how well the medicine is working. You should call your doctor right away if you are taking warfarin or heparin and have easy bruising or bleeding.

Thrombolytics are medications given to quickly dissolve the blood clot. They are used to treat large clots causing severe symptoms. Because they can cause sudden bleeding, they are only used in life-threatening situations.

Thrombin inhibitors are new medications that interfere with the clotting process. They are used in treating some types of clots and for patients who cannot take heparin.

Vena cava filters are used when you cannot take medications to thin your blood, or if you are taking blood thinners and continue to develop clots. The filter can prevent blood clots from moving from the vein in your legs to the lung (pulmonary embolism). The filter is inserted inside a large vein called the vena cava. It can catch the clots as they try to move through the body to the lungs. This treatment will prevent a pulmonary embolism, but will not stop you from developing more clots.

Your doctor may prescribe graduated compression stockings to reduce the chronic swelling that can occur in the leg after a blood clot has developed. The swelling is due to damage to the valves in the leg veins.

Compression stockings are worn on the legs from the arch of the foot to just above or below the knee. These stockings are tight at the ankle and become looser as they go up the leg. This causes a gentle compression (or pressure) up your leg. They have some side effects:
  • They can be uncomfortable when worn all day
  • They can be hot
  • They may be difficult to put on, especially for older adults and overweight people.
Much of the treatment for deep vein thrombosis takes place at home. It is important to:
  • Take medications correctly.
  • Have blood work drawn as directed by your doctor.
  • Avoid activities that may cause a serious injury.
  • Talk to your doctor before taking any other medications, especially over-the-counter medications.
  • Ask your doctor about your diet. Certain foods affect how well your anticoagulant works.

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Frequently Asked Questions About Deep Vein Thrombosis

If I have mild symptoms of a deep vein thrombosis, can I wait and see if the clot will go away on its own?

  • No. Not treating a deep vein thrombosis can cause very serious complications. If you think you have the symptoms or are unsure if you have the symptoms, see a doctor right away.
Are there any foods that change the way my medications work?
  • Yes, foods that contain Vitamin K can change how well warfarin (coumadin) will work. This vitamin is found in green leafy vegetables and in some oils like canola and soybean oil. It is best if you eat a well-balanced healthy diet that doesn't vary. For example, you should not make up for having no vegetables one week by eating extra helpings of vegetables the next week.
I hear that alcohol can thin my blood. Can I drink alcohol while taking anticoagulants?
  • It is important that you discuss with your doctor what amount of alcohol is safe for you to drink.
Do I need to restrict my activities while I am being treated for a deep vein thrombosis?
  • You should discuss your activities with your doctor. In general, your activities do not need to be restricted.
Can I take over-the-counter medications while taking anticoagulants (blood thinners)?
  • Some over-the-counter medications, such as vitamin K in multivitamins, may change the way your medications work. Aspirin can also thin your blood. Taking two medications (even if one is over-the-counter) that thins your blood may increase your risk for excessive bleeding. Always check with your health care team before taking any other medications while taking anticoagulants.
Why do I need to have blood testing?
  • While you are taking anticoagulants, your doctor will need to carefully monitor your clotting ability. Blood tests will measure how quickly your blood clots or if your blood is clotting too slowly. If your lab tests show that your blood is clotting too slowly or too quickly, your medications may be changed or adjusted.

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Deep Vein Thrombosis