Deep Vein Thrombosis

Deep Vein Thrombosis
(DVT, Blood Clot in the Legs)

Heart Disease (Coronary Artery Disease) Slideshow

Medical Author: Benjamin C. Wedro, MD, FAAEM
Medical Editor: Melissa Conrad Stöppler, MD

• Introduction to deep vein thrombosis
• What are the causes of deep vein thrombosis?
• What are the symptoms of deep vein thrombosis?
• When should I seek medical care for deep vein thrombosis?
• How is deep vein thrombosis diagnosed?
• What is the treatment for deep vein thrombosis?
• What are the complications of deep vein thrombosis?
• Can deep vein thrombosis be prevented?
• Patient Discussions: Deep Vein Thrombosis - Symptoms Experienced

Introduction to deep vein thrombosis (DVT)

Arteries have thin muscles within their walls to be able to withstand the pressure of the heart pumping blood to the far reaches of the body. Veins don't have a significant muscle lining, and there is nothing pumping blood back to the heart except physiology. Blood returns to the heart because the body's large muscles squeeze the veins as they contract in their normal activity of moving the body. The normal activities of moving the body returns the blood back to the heart.

There are two types of veins in the leg; superficial veins and deep veins. Superficial veins lie just below the skin and are easily seen on the surface. Deep veins, as their name implies, are located deep within the muscles of the leg. Blood flows from the superficial veins into the deep venous system through small perforator veins. Superficial and perforator veins have one-way valves within them that allow blood to flow only in the direction of the heart when the veins are squeezed.

A blood clot (thrombus) in the deep venous system of the leg is not dangerous in itself. The situation becomes life-threatening when a piece of the blood clot breaks off (embolus, pleural=emboli), travels downstream through the heart into the pulmonary circulation system, and becomes lodged in the lung. Diagnosis and treatment of a deep venous thrombosis (DVT) is meant to prevent pulmonary embolism.

Clots in the superficial veins do not pose a danger of causing pulmonary emboli because the perforator vein valves act as a sieve to prevent clots from entering the deep venous system. They are usually not at risk of causing pulmonary embolism.

Picture of a blood clot is formed

What are the causes of deep vein thrombosis?

Blood is meant to flow; if it becomes stagnant there is a potential for it to clot. The blood in veins is constantly forming microscopic clots that are routinely broken down by the body. If the balance of clot formation and resolution is altered, significant clotting can occur. A thrombus can form if one, or a combination of the following situations is present:

Immobility

• Prolonged travel and sitting, such as long airplane flights ("economy class syndrome"), car, or train travel
  
  
• Hospitalization
  
  
• Surgery
  
  
• Trauma to the lower leg with or without surgery or casting
  
  
• Pregnancy, including 6-8 weeks post partum
  
  
• Obesity

Hypercoagulability (coagulation of blood faster than usual)

• Medications (for example, birth control pills, estrogen)
  
  
• Smoking
  
  
• Genetic predisposition
  
  
• Polycythemia (increased number of red blood cells)
  
  
• Cancer

Trauma to the vein

• Fracture to the leg
  
  
• Bruised leg
  
  
• Complication of an invasive procedure of the vein

Deep Vein Thrombosis - Symptoms Experienced

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