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Symptoms and Signs of DVT (Deep Vein Thrombosis, Blood Clot in the Leg) Warning Signs, Symptoms, Causes, and Treatments

Doctor's Notes on DVT (Blood Clot in the Leg, Deep Vein Thrombosis) Symptoms, Causes, and Treatments

Deep vein thrombosis (DVT) is a condition in which blood clots (thrombi, singular = thrombus) for in the deep veins of the extremities, usually the legs. There are a number of potential causes of DVT. Causes include broken bones, other trauma to a limb, immobility (such as prolonged bedrest or long flights), medications, smoking, genetic predisposition, and certain cancers.

Deep vein thrombosis may not cause any associated symptoms or signs. Symptoms of a deep vein thrombosis in a leg are swelling of the involved leg, leg pain, tenderness, redness, and warmth. A DVT (thrombus) in the deep veins of the leg becomes dangerous if a piece of the blood clot breaks off and passes through the blood stream, through the heart, and into the pulmonary arteries. This is known as a pulmonary embolism.

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Medically Reviewed on 3/25/2019

DVT (Blood Clot in the Leg, Deep Vein Thrombosis) Symptoms, Causes, and Treatments Symptoms

Signs and symptoms of a blood clot in the leg or deep vein thrombosis occur in the affected leg when a clot obstructs blood flow and causes inflammation. Signs and symptoms of DVT may include:

  1. Swelling
  2. Gradual onset of pain
  3. Redness
  4. Warmth to the touch
  5. Worsening leg pain when bending the foot
  6. Leg cramps, especially at night, and often starting in the calf
  7. Bluish or whitish discoloration of skin

Some people with deep vein thrombosis do not experience any symptoms.

DVT (Blood Clot in the Leg, Deep Vein Thrombosis) Symptoms, Causes, and Treatments Causes

Three factors may lead to formation of a clot inside a blood vessel:

  1. Damage to the inside of a blood vessel due to trauma or other conditions
  2. Changes in normal blood flow, including unusual turbulence, or partial or complete blockage of blood flow
  3. Hypercoagulability, a rare state in which the blood is more likely than usual to clot

Any event or condition that can lead to blood vessel damage, hypercoagulability, or change in blood flow can potentially cause deep vein thrombosis. The more common risk factors are:

  • Prolonged sitting, such as during a long plane flight or car ride
  • Prolonged bed rest or immobility, such as after injury or during illness (for example stroke)
  • Recent surgery, particularly orthopedic (especially hip, leg, or , knee such as knee or hip replacement), gynecologic, heart, or abdominal surgery
  • Recent trauma to the lower body, such as fractures of the bones of the hip, thigh, or lower leg
  • Obesity
  • Heart attack or heart failure
  • Pregnancy or recent childbirth
  • Being at very high altitude, greater than 14,000 feet
  • Use of estrogen therapy or birth control pills
  • Cancer
  • Rare inherited genetic conditions that lead to changes in certain blood clotting factors
  • Certain heart or respiratory conditions
  • Advanced age
  • Medical conditions that affect the veins such as vasculitis (inflammation of the vein walls), varicose veins
  • Superficial venous thrombosis (SVT) occurs when a blood clot forms in a superficial vein near the surface of the body. While not the same as DVT (which occurs in deep veins) it can be a risk factor for DVT/PE
  • Disseminated intravascular coagulation (DIC), a medical condition in which blood clotting occurs inappropriately, usually is caused by overwhelming infection or organ failure

If an individual has one deep vein thrombosis, they are 33% more likely to develop a second deep vein thrombosis within 10 years.

DVT in Pictures Symptoms of Deep Vein Thrombosis, Beyond Leg Pain and More Slideshow

DVT in Pictures Symptoms of Deep Vein Thrombosis, Beyond Leg Pain and More Slideshow

Deep vein thrombosis is a blood clot that forms inside a vein, usually deep within your leg. About half a million Americans every year get one, and up to 100,000 die because of it. The danger is that part of the clot can break off and travel through your bloodstream. It could get stuck in your lungs and block blood flow, causing organ damage or death.


Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.