A Blood Clot in the Leg

What is DVT and What Problems Does it Cause? 

A Deep Vein Thrombosis (DVT) is the formation of a blood clot within a deep vein of the body, usually a leg vein. There are three common consequences of a DVT episode:

  1. A DVT can break free and flow within the bloodstream to the lungs (this complication is called Pulmonary Embolism or PE). When PE occurs, it is often fatal. 
  2. DVT survivors often experience long-term pain, swelling, heaviness, fatigue, skin changes, and/or open sores on the legs, a complication called the Post-Thrombotic Syndrome (PTS). 
  3. Patients with DVT often experience pronounced pain, swelling, cramping, and/or tenderness of the involved leg during the initial episode.

What Causes a Blood Clot and Who is at Risk for DVT?

Between 350,000 and 600,000 people develop DVT each year in the U.S. (1). PE is estimated to lead to over 100,000 deaths each year in the U.S.  PTS develops in 25-50% of patients with a first episode of DVT, which is between 50,000 and 100,000 patients per year (2). About 30% of DVT patients will later develop additional DVT episodes (3). DVT affects men and women at all ages. In general the risk of developing DVT increases significantly as we get older. DVT can also affect newborns, children and pregnant women. 

People who develop DVT often have one or more of the following Risk Factors: 


  1. Recent major trauma (e.g. car accident with bony fractures)
  2. Recent major surgery
  3. Cancer
  4. Immobilization due to medical illness, paralysis, or other condition
  5. Pregnancy
  6. Hormonal treatments (e.g. birth control pills)
  7. Disorders of the blood clotting system (often inherited) 


Two-thirds of DVT cases occur in people who are hospitalized for surgery or a medical illness.


Can DVT Be Prevented? 

YES. Injectable blood-thinning drugs and mechanical leg compression devices are highly effective in preventing DVT and PE, and are widely available (4). 

PE is the most common preventable cause of death in hospitalized patients. Unfortunately, doctors and hospitals often fail to properly prescribe the above preventive measures for patients who are at risk. Most patients are not familiar with DVT and do not know that they are at risk. When being admitted to the hospital for surgery or a medical illness, patients and family members should ask their physicians and nurses what measures are being taken to prevent DVT. 


1. The Surgeon General’s Call to Action to Prevent Deep Vein Thrombosis and Pulmonary Embolism. U.S. Department of Health and Human Services report, 2008.

2. Kahn SR, Shrier I, Julian JA, et al. Determinants and time course of the postthrombotic syndrome after acute deep venous thrombosis. Ann Intern Med 2008; 149(10):698-707.

3. Prandoni P, Lensing A, Cogo A, et al. The long term clinical course of acute deep venous thrombosis. Ann Intern Med 1996; 125:1-7.

4. Kearon C, Kahn SR, Agnelli G, Goldhaber SZ, Raskob G, Comerota AJ. Antithrombotic therapy for venous thromboembolic disease. American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Ed). Chest 2008; 133:454S-545S.