What is Deep Vein Thrombosis (DVT)?

Deep vein thrombosis (DVT), is a blood clot that forms in larger blood vessels usually deep in the legs. Blood clots occur when blood thickens and clumps together. Most deep vein blood clots occur in the lower leg or thigh but, they can also occur in other parts of your body.

A blood clot can break apart and travel through the bloodstream. The loose clot is called an embolus and can travel to an artery in the lungs and block blood flow. This condition is called a pulmonary embolism or (PE). A pulmonary embolus is a serious condition because it can damage the lungs and other organs in the body and cause sudden death.

What Causes Deep Vein Thrombosis?

The inner lining of the vein is damaged. Injuries sustained by chemical, physical, or biological factors can damage veins. Examples are surgery, inflammation, immune responses, and serious injuries.

Blood flow becomes slow especially after surgical procedure, prolonged inactivity, or traveling for a long time. The blood is thicker or more likely to clot than normal. There are some inherited conditions (Factor V Leiden) that increase the risk of blood clotting. Birth control pills or hormones can also increase the risk of clotting.

Signs and Symptoms of Deep Vein Thrombosis (DVT)

Only half of people with DVT have signs and symptoms and these occur in the leg from the blood clot. They include: Pain or tenderness in the leg, swelling in the leg, warmth in the area of the leg that is swollen and painful, and reddened leg.

With pulmonary embolism (PE) the signs and symptoms include pain when breathing, shortness of breath & coughing up blood.

How is Deep Vein Thrombosis Diagnosed?

The doctor will need to examine you and this includes questions about symptoms, medical history, physical exam and labs. The doctor will diagnose deep vein thrombosis (DVT) based on your medical history, a physical exam, and test results. The doctor will also identify your risk factors and rule out other causes of your symptoms.

Common exams and tests include:

D-dimer test

D-dimer is a chemical that is released by blood clots as they start to disintegrate. If the D-dimer test is normal, then a blood clot is not present. The test does not tell the doctor the location where the blood clot might be. For example, the test is also positive in a person that has a bruise or those who have undergone recent surgery.


An ultrasound is the most common test for diagnosing deep vein blood clots. An ultrasound can detect blood clots or a blockage of blood flow, especially in larger, more proximal upper leg veins. A small hand-held probe is pressed against the patient’s skin to see if there are any blood clots and locate the obstruction. An ultrasound test is non-invasive and painless. This test uses sound waves to create images of blood flowing through arteries and vein in the affected leg.


Your doctor may order one of these tests if the ultrasound doesn’t provide a clear diagnosis. With venography, dye is injected into a vein in the affected leg. The dye makes the vein visible on x- ray and will show if blood flow is slow in the vein, which may suggest a blood clot. Cat scans and magnetic resonance imaging (MRI) MRI or cat scans are other tests commonly used to look for abnormalities in the blood vessel as well as surrounding area.

When to Seek Medical Care

Call your doctor if you have signs and symptoms of swelling, pain and inflamed superficial veins on the arms or legs.

Seek immediate medical care for Deep Vein Thrombophlebitis.

Go to the emergency room or your doctor for evaluation if you have the following:

  • Fever with any symptoms in an arm or leg
  • Pain and swelling in an arm or leg
  • Chest pain and shortness of breath
Risk Factors for Deep Venous Thrombophlebitis (DVT)
  • Prolonged inactivity
  • Sedentary lifestyle
  • Obesity
  • Cigarette smoking
  • Hormone replacement or birth control pills
  • Pregnancy
  • Medical conditions such as cancer or blood disorders
  • Varicose veins may be associated with superficial phlebitis
How Can Deep Vein Thrombosis Be Prevented?
  • See your doctor for regular checkups
  • Take your medications as directed
  • Get up and move around after surgery or illness
  • Exercise your leg muscles during long trips in a car or plane
  • Wear mile compression stockings when traveling