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What is pulmonary embolism?

A pulmonary embolism (PE) is an obstruction caused by a blood clot (thrombus) in the pulmonary artery that has traveled through the bloodstream (usually from a vein in the legs). A blood clot in the deep veins of the legs or elsewhere in the body is called a deep venous thrombosis (DVT). PE most often is a complication of DVT.

The dangers of a PE are:

  • Damage to part of your lungs because of a lack of blood flow to the tissue; this damage may lead to pulmonary hypertension (increased pressure in the pulmonary arteries)
  • Low oxygen levels in your blood
  • Damage to other organs because of a lack of oxygen

In patients with a large clot, obstructed circulation may produce shock or sudden death.


Symptoms of pulmonary embolism depend upon the size of the clot and may include:

  • Chest pain
  • Rapid or irregular heart rate
  • Sudden shortness of breath and other breathing problems
  • Sudden coughing, sometimes with blood

It’s also possible to have PE and not have any signs or symptoms.


Pulmonary embolism is a serious condition caused by a blood clot that has traveled from the lung through the heart, and most likely originated from veins in the legs or pelvis. The clots become wedged in a vessel that is too small to allow it to continue farther, impeding the blood flow through the heart and lungs. Inciting factors may include:

  • Cancer
  • Congestive heart failure
  • Surgery damage
  • Breaking a bone
  • Long-duration travel in an airplane or any other type of vehicle
  • Being bedridden for an extended time
  • Medications that increase the risk of blood clotting
  • Injury

Risk factors

Risk factors for pulmonary embolism include:

  • Age: For every 10 years after age 60, the risk of having PE doubles
  • A previous case of DVT
  • Stroke, paralysis, chronic heart disease or high blood pressure
  • Smoking
  • Recent cancer treatment
  • Having had a central venous catheter
  • Certain inherited conditions, such as Factor V Leiden
  • Pregnancy and the six-week period after pregnancy
  • Taking hormone therapy or birth control pills
  • Being overweight or obese


Emergency room doctors often detect a PE with a radiologist’s help. During a physical exam, a doctor will check your legs for signs of DVT, as well as checking your blood pressure, heart and lungs. Some of the tests that may be used to diagnose PE are:

  • Ultrasound
  • Computed tomography (CT) scan
  • Lung ventilation/perfusion scan
  • Pulmonary angiography
  • Blood tests
  • Echocardiography
  • Electrocardiogram (EKG)
  • Chest X-ray
  • Chest MRI (magnetic resonance imaging)


Preventive measures for pulmonary embolism include:

  • Exercise your lower leg muscles if you’re sitting for a long time while traveling.
  • ​Move around as soon as you’re able after having surgery or being ill.
  • Take medicines to prevent clots after some types of surgery (as your doctor prescribes).