Definition

Deep vein thrombosis is a blood clot in a vein deep within the body. Veins are blood vessels with a system of valves that helps prevent the blood from flowing backwards. The muscles in the arms and legs contract and help force the blood through the veins back to the heart.

Deposits of red blood cells and clotting elements in the blood can accumulate in a vein and lead to blood clot formation. Clots usually occur in the legs but can occur in other locations. As the clot grows, it blocks blood flow in the affected vein.

	Deep Vein Thrombosis
	© 2008 Nucleus Medical Art, Inc.

Causes

Several factors contribute to clot formation, including:

• Slow blood flow, often due to lying or sitting still for an extended period of time
• Pooling of blood in a vein, often due to:
  • Immobility
  • Medical conditions
  • Damage to valves in a vein or pressure on the valves, such as during pregnancy
• Injury to a blood vessel
• Clotting problems (can occur due to aging or disease)
• Catheters placed in a vein

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

• Not moving your body
• Hospitalization
• Surgery, especially involving bones or joints
• Medical conditions such as:
  • Varicose veins
  • Cancer
  • Heart failure
  • Heart attack
  • Inflammatory bowel disease
  • Blood disorders
• Obesity
• History of deep vein thrombosis
• Taking birth control pills or estrogen therapy
• Pregnancy

Symptoms

Symptoms occur when:

• The clot interferes with blood flow in the vein
• Local inflammation occurs
• A clot breaks free and travels to the lungs

Some patients may not experience any symptoms until the clot moves to the lungs, a condition called pulmonary embolism.

Symptoms of deep vein thrombosis may include:

• Pain
• Swelling of a limb
• Tenderness along the vein
• Warmth
• Redness, paleness, or blueness of the skin of the affected limb

Diagnosis

The doctor will ask about your symptoms and medical history, and perform a physical exam.

Tests may include:

Duplex venous ultrasound —uses sound waves to detect changes in blood flow

Venography —x-rays taken after dye is injected into a small vein to show areas of normal and abnormal blood flow

Impedance plethysmography—measures changes in blood volume in the veins as a blood pressure cuff wrapped around the thigh is inflated and deflated

Treatment

Treatment aims to:

• Prevent pulmonary embolism
• Stop the clot from growing
• Dissolve the clot (sometimes)

Treatments include:

Supportive Care

This may include:

• Resting in bed
• Elevating the affected limb above the heart
• Wearing compression stockings as recommended by your doctor

A recent study among 103 patients recently admitted to the hospital with deep venous thrombosis suggested that strict bed rest may not be necessary. In fact, early ambulation (walking) may be beneficial as long as adequate treatment with heparin (see below) and compression stockings are provided. *

Medications

Anticoagulant drugs to prevent additional clot formation include:

• Heparin injection—fast-acting drug that prevents more clot formation (given for several days)
• Warfarin (taken by mouth)—slowly prevents more clot formation (usually given for several months)
• Fibrinolytic enzymes—helps to dissolve a major clot. These include:
  • Streptokinase
  • Urokinase
  • TPA

Surgery

In certain situations, doctors may place a filter in the inferior vena cava, a major vein returning blood from the lower body to the heart. The filter may trap any clots that break loose and travel toward the lungs.

Prevention

General prevention measures include:

• Not sitting for long periods, such as in a car or airplane or at a computer (get up frequently and move around.)
• Not smoking

If you are admitted to the hospital, talk to your doctor about how to prevent blood clots, such as:

• Getting out of bed and walking as soon as possible during your recovery
• If you are restricted to bed:
  • Doing range of motion exercises in bed
  • Changing your position at least every two hours
• Wearing compression stockings, which promotes venous blood flow
• Taking anticoagulant medication if advised by your doctor
• Using a pneumatic compression device (a device that uses air to compress your legs and help improve venous blood flow)

RESOURCES:

American Heart Association
http://www.americanheart.org

American Venous Forum
http://www.venous-info.com/index.html

CANADIAN RESOURCES:

BC Healthguide
http://www.bchealthguide.org

Canadian Heart and Stroke Association
http://ww1.heartandstroke.ca

Transport Canada
http://www.tc.gc.ca

References:

AHA Medical/Scientific Statement: Management of Deep Vein Thrombosis and Pulmonary Embolism; 1996.

Buller HR. Agnelli G. Hull RD. Hyers TM. Prins MH. Raskob GE. Antithrombotic therapy for venous thromboembolic disease: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest. 126(3 Suppl):401S-428S, 2004 Sep.

Cecil Textbook of Medicine . 21st ed. W.B. Saunders Company; 2000.

Church V. Staying on guard for DVT and PE. Nursing . Feb 2000.

Conn's Current Therapy 2001 . 53rd ed. W.B. Saunders Company; 2001.

Emergency Medicine: Concepts and Clinical Practice . 4th ed. Mosby-Year Book, Inc; 1998.

Geerts WH. Pineo GF. Heit JA. Bergqvist D. Lassen MR. Colwell CW. Ray JG. Prevention of venous thromboembolism: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest. 126(3 Suppl):338S-400S, 2004 Sep.

Harrison's Principles of Internal Medicine . 14th ed. The McGraw-Hill Companies; 2000.

Ramzi DW. Leeper KV. DVT and pulmonary embolism: Part I. Diagnosis. American Family Physician . 69(12):2829-36, 2004 Jun 15.

Ramzi DW. Leeper KV. DVT and pulmonary embolism: Part II. Treatment and prevention. American Family Physician . 69(12):2841-8, 2004 Jun 15.

Segal JB. Streiff MB. Hoffman LV. Thornton K. Bass EB. Management of venous thromboembolism: a systematic review for a practice guideline. Annals of Internal Medicine . 146(3):211-22, 2007 Feb 6.

*Updated section on Supportive Care on 10/27/06 according to the following study, as cited by DynaMed's Systematic Literature Surveillance : Junger M, Diehm C, Storiko H, Hach-Wunderle V, Heidrich H, Karasch T, et al. Mobilization versus immobilization in the treatment of acute proximal deep venous thrombosis: a prospective, randomized, open, multicentre trial. Curr Med Res Opin . 2006 Mar;22(3):593-602.

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