Deep Vein Thrombosis

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What is deep vein thrombosis?

Deep vein thrombosis (DVT) is a serious condition in which a blood clot called a thrombus develops in a vein located deep within the body. A deep vein thrombosis usually forms within a large vein in the thigh or calf area, or sometimes the pelvic area. DVT can also develop in the arm, but this is rare.

Your veins are responsible for transporting oxygen-poor blood from the tissues of the body back to the heart. Blood in the veins is under lower pressure than blood in the arteries. Because of this, blood in the veins can pool and form blood clots more easily than in the arteries.

Blood clots are most likely to form in the legs, where the effects of gravity can increase the pooling of blood. This can occur when you are sitting or lying in one position for an extended period of time, such as during recuperation from a disease or surgery. Certain medications and medical conditions can also cause a DVT by increasing the blood’s ability to clot or encouraging the clotting of blood in a vein. Normally, muscle movement in the legs helps move the blood through the veins and reduces the risk of developing blood clots.

DVT can lead to a dangerous, potentially life-threatening complication known as a pulmonary embolism. This occurs when a blood clot breaks off and travels through the blood stream and lodges in the lungs, obstructing blood flow. DVT and pulmonary embolism are major health threats. The U.S. Centers for Disease Control and Prevention (CDC) estimates that between 350,000 and 600,000 Americans develop deep vein thrombosis and pulmonary embolisms each year (Source: CDC).

DVT and pulmonary embolism are life-threatening emergency conditions. Seek immediate medical care (call 911) if you, or someone you are with, have symptoms of DVT or pulmonary embolism, such as unexplained leg pain or swelling, difficulty breathing, chest pain, or change in consciousness.


What are the symptoms of deep vein thrombosis?

In many cases, a deep vein thrombosis (DVT) can develop without any obvious symptoms. When symptoms do occur, they can include leg pain, warmth, redness or swelling.

A serious complication of DVT is a pulmonary embolism in which the blood clot travels to the lung. The symptoms of a pulmonary embolism are more evident than those associated with DVT. In fact, many people are not diagnosed with DVT until after they develop the hallmark symptoms of a pulmonary embolism, including shortness of breath and coughing blood.

Serious symptoms that might indicate a life-threatening condition

Deep vein thrombosis is a serious condition that can rapidly result in the development of an embolism that travels through the blood stream and obstructs blood supply to the lungs. Seek immediate medical care (call 911) if you, or someone you are with, have any of the following symptoms:

  • Change in level of consciousness or alertness, such as passing out (fainting) or unresponsiveness

  • Chest pain, chest tightness, chest pressure, or palpitations

  • Coughing blood

  • Rapid heart rate (tachycardia)

  • Respiratory or breathing problems, such as shortness of breath, difficulty breathing, labored breathing, wheezing, not breathing, or choking

  • Unexplained tenderness or cramp-like pain in the thigh or calf, or pain behind the knee, especially if accompanied by increased skin warmth or redness.

  • Weak or absent pulse


What causes deep vein thrombosis?

Deep vein thrombosis (DVT) is a vascular disease that occurs when a blood clot called a thrombus forms in a deep vein within the thigh, calf or pelvis. Blood clots can also develop in the arm and other parts of the body. Blood clots can be caused by diseases, disorders, medical treatments, and conditions that increase the ability of blood to clot, encourage the formation of a clot in a vein, or decrease blood circulation. Poor circulation can allow blood in the veins to pool and increase the risk of clotting.

Causes of DVT include:

  • Conditions that increase the blood’s capacity to clot, including certain rare inherited disorders, nephrotic syndrome, and polycythemia vera (increased production of blood cells that causes thickening of the blood)

  • Immobility due to situations such as bed rest, long periods of sitting or travel, or having a cast

  • Injury to the inner lining of a vein. This can occur due to such factors as surgery, serious fractures, certain medications, needle puncture to the vein, or inflammation caused by vasculitis.

  • Medications that increase blood clotting, such as birth control pills and hormone replacement therapy

What are the risk factors for deep vein thrombosis?

A number of factors are thought to increase your chances of developing deep vein thrombosis (DVT). Risk factors include a variety of conditions that slow or disrupt the flow of blood in the veins or damage the inside of a vein, resulting in the formation of a blood clot. Your chances of developing deep vein thrombosis increase if you have more than one risk factor including:

  • Advanced age, particularly people older than 60 years, although individuals of any age can develop deep vein thrombosis

  • Cancer and cancer treatment

  • Congestive heart failure

  • Fractures, especially in the leg or pelvis

  • Heart and lung diseases

  • Immobility due to situations such as bed rest, long periods of sitting or travel, or having a cast

  • Injuries to deep veins

  • Male gender

  • Medications, such as birth control pills and estrogen. Your risk from these medications increases if you smoke.

  • Personal or family history of blood clots or diseases that cause blood clots

  • Placement of a catheter in a large vein or having a pacemaker

  • Pregnancy and the postpartum period

  • Recent surgery, especially that of the hip, legs, abdomen, or female reproductive organs

  • Smoking

Reducing your risk of deep vein thrombosis

You can reduce your risk of developing deep vein thrombosis by following your treatment plan for such conditions as cancer and heart and lung diseases. You can also lower your risk by:

  • Appropriate use of blood-thinning medication in susceptible individuals

  • Avoiding dehydration

  • Avoiding intravenous (IV) drug use

  • Maintaining a healthy weight and not being overweight or obese

  • Not sitting for long periods without movement, such as when traveling or working at a computer

  • Not smoking

  • Use of compression stockings when bedridden or as a passenger during international air travel


How is deep vein thrombosis treated?

Deep vein thrombosis can be treated and often prevented. Treatment and prevention plans are individualized to the severity of the disease; your age, sex, and medical history; your risk of complications; and other factors. The main treatment goals are to stop the blood clot (thrombus) from growing larger, prevent it from traveling to the lungs, and reduce future clotting risks.

Typically, deep vein thrombosis is treated and may be prevented with medications and other treatments that can include:

  • Anticoagulants, which are medications that “thin” the blood. Anticoagulants prevent new clots from forming or older ones from increasing in size until the body can break down and absorb the clot. Commonly prescribed anticoagulants include heparin and warfarin (Coumadin). When taking anticoagulants, it is important to follow your health care provider’s instructions exactly, because of the possibility for serious side effects such as bleeding. You will need periodic blood tests to determine if a dose adjustment is needed.

  • Compression stockings, which improve blood flow in your legs

  • Thrombolytics, which are medications that can dissolve a clot. Thrombolytics are only used in specific types of serious cases because of the potential for serious adverse effects.

  • Vena cava filter, which is a special type of filter that is placed in the large vein that empties into the heart. The filter catches emboli before they can reach the lungs and cause serious complications.

What are the potential complications of deep vein thrombosis?

Complications of deep vein thrombosis are serious and even life threatening. You can minimize the risk of complications by following the treatment plan you and your health care professional design specifically for you. Complications include:

  • Post-thrombotic syndrome, which affects nearly one-third of all those with deep vein thrombosis. Symptoms include pain, skin discoloration, and long-term swelling in the affected leg. In more severe cases, you may develop scaling or ulcers in affected areas, as well as disability.

  • Pulmonary embolism

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2019 Jan 4
  1. Deep Venous Thrombosis. Medline Plus, a service of the National Library of Medicine National Institutes of Health.
  2. What Is Deep Vein Thrombosis? National Heart Ling and Blood Institute.
  3. Deep Vein Thrombosis/Pulmonary Embolism (DVT/PE). Centers for Disease Control and Prevention.
  4. Post-Thrombotic Syndrome. Vascular Disease Foundation.
  5. Tierney LM Jr., Saint S, Whooley MA (Eds.) Current Essentials of Medicine (4th ed.). New York: McGraw-Hill, 2011.
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