Share this NATF page   

What is Thrombosis?

Risk Factors   |   Thrombosis FAQs   |   Recently Diagnosed 

Thrombosis is the formation of a blood clot within a blood vessel causing a partial or total obstruction; it prevents blood from flowing normally through the circulatory system. An abnormally increased tendency toward blood clotting (caused by genetic, environmental, or unknown factors), endothelial cell injury of the vessel wall (exacerbated by infection or trauma), and static blood flow contribute to the formation of blood clots.

Partial or complete detachment of the thrombus from the blood vessel wall allows the clot to embolize to vital organs such as the brain, heart, lungs, or leg arteries. The free-flowing blood clot lodges within the vasculature and obstructs blood flow. Life-threatening pathological conditions can occur as a result, such as stroke, heart attack, pulmonary embolism, or limb-threatening gangrene.

Venous thromboembolism (VTE) is a disease that includes both deep vein thrombosis (DVT) and pulmonary embolism (PE).  Risk factors that contribute to VTE are varied and include:
  • Immobilization
  • Hypercoagulability
  • Vessel wall damage
  • Age
  • Surgery (especially orthopedic surgery and total knee replacement)
  • Cancer
  • Heredity (including the Factor V Leiden genetic mutation)
  • Pregnancy
  • Increased estrogen levels (due to oral contraception or hormone replacement therapy)
  • Obesity
  • Smoking
  • Crohn's Disease

Arterial thrombosis within the coronary arteries leads to myocardial infarction (heart attack), while obstruction of the cerebral vasculature causes stroke.  It is important to note that venous and arterial thromboses share many of the same risk factors, including cigarette smoking, hypertension, and diabetes mellitus.

Deep vein thrombosis is the most common form of venous thrombosis. Signs and symptoms of DVT include:

  • Discomfort, heaviness, pain aching, throbbing, itching, or warmth in the legs
  • Skin changes in the leg, such as discoloration, thickening, or ulceration
  • Swelling of the legs, ankles, or feet

Post-thrombotic syndrome (PTS) develops in at least half of patients with a DVT. Chronic leg swelling, calf pain, calf heaviness/fatigue, skin discoloration, and/or venous ulcers in the affected limb characterize PTS. Quality of life is significantly impaired in patients with PTS.

Pulmonary embolism (PE) is a complication from DVT. Symptoms and signs of PE include:

  • Sudden shortness of breath
  • Chest pain
  • Coughing up blood
  • Rapid or irregular heart rate
  • Lightheadedness                     

About NATF





Giving to NATF

North American Thrombosis Forum
368 Boylston Street
Brookline, MA 02445

617 - 730 - 4120

NATF is a 501(c) nonprofit

Contact Us

© 2012 North American Thrombosis Forum

Web Development by MTC