What is thrombosis?

Thrombosis occurs when blood clots block your blood vessels. There are 2 main types of thrombosis:

  • Venous thrombosis is when the blood clot blocks a vein. Veins carry blood from the body back into the heart.
  • Arterial thrombosis is when the blood clot blocks an artery. Arteries carry oxygen-rich blood away from the heart to the body.

What causes thrombosis?

Venous thrombosis may be caused

  • Disease or injury to the leg veins
  • Not being able to move around (immobility) for any reason
  • A broken bone (fracture)
  • Certain medicines
  • Obesity
  • Inherited disorders, or a greater likelihood of having a certain disorder based on your genes
  • Autoimmune disorders that make it more likely your blood will clot
  • Medicines that increase your risk of
    clotting(such as certain birth control medicines

Arterial thrombosis may be caused
by a hardening of the arteries (atherosclerosis). This happens when fatty or calcium
deposits cause artery walls to thicken. This can lead to a buildup of fatty material
(plaque) in the artery walls. This plaque can suddenly burst (rupture), followed by a
blood clot.

Arterial thrombosis can occur in the arteries that supply blood to the heart muscle (coronary arteries). This can lead to a heart attack. When arterial thrombosis occurs in a blood vessel in the brain, it can lead to a stroke.

Who is at risk for thrombosis?

Many of the risk factors for venous and arterial thrombosis are the same.

Risk factors for venous thrombosis may include:

  • A family history of a blood clot in a
    vein deep in the body (deep vein thrombosis or DVT)
  • A history of DVT
  • Hormone therapy or birth control pills
  • Pregnancy
  • Injury to a vein, such as from surgery, a broken bone, or other trauma
  • Lack of movement, such as after surgery or on a long trip
  • Inherited blood clotting disorders
  • A central venous catheter
  • Older age
  • Smoking
  • Being overweight or obese
  • Some health conditions, such as cancer, heart disease, lung disease, or Crohn’s disease

Risk factors for arterial thrombosis may include:

  • Smoking
  • Diabetes
  • High blood pressure
  • High cholesterol
  • Lack of activity and obesity
  • Poor diet
  • Family history of arterial thrombosis 
  • Lack of movement, such as after surgery or on a long trip
  • Older age

What are the symptoms of thrombosis?

Symptoms may vary a bit for each
person. Symptoms may include:

  • Pain in one leg, usually the calf or
    inner thigh
  • Swelling in the leg or arm
  • Chest pain
  • Numbness or weakness on one side of
    the body
  • Sudden change in your mental
  • Cold arm or leg

The symptoms of thrombosis may look like other blood disorders or health problems. Always see your healthcare provider for a diagnosis.

How is thrombosis diagnosed?

Your healthcare provider will ask
about your health history and give you a physical exam. Other tests may include:

  • Ultrasound. This test uses sound
    waves to check the blood flow in your arteries and veins.
  • Blood tests. These may include tests
    to see how well your blood can clot.
  • Venography. For this test, a dye is
    injected into your veins. Then X-rays are taken to show blood flow and look for
    clots. The dye makes your veins easier to see on the X-rays.
  • MRI, MRA or CT scan. The imaging
    procedure that is used will depend on the type of blood clot you have and where it is
  • Angiography. This imaging test uses a contrast dye to look at
    the blood vessels.