What is pulmonary embolism?

A pulmonary embolism occurs when the pulmonary artery becomes blocked and the supply of blood to the lungs is cut off. Typically, it is caused by a blood clot that has broken off from the vessels in the legs or other parts of the body and travels to the lungs.

Pulmonary embolisms can be life-threatening and affect approximately 1 in every 1,000 people in the United States annually. If found early, a pulmonary embolism can be treated. If left untreated, a pulmonary embolism can lead to cardiac arrest, sudden death, shock, abnormal heart rhythms or pulmonary hypertension.

Causes of pulmonary embolism

A pulmonary embolism can occur when a blood clot blocks the pulmonary artery that leads to the lungs. Most blood clots start in the legs or arms, which is called deep vein thrombosis (DVT). The blood clot breaks free from a vessel in the leg or arm and travels to the lungs and blocks the flow of oxygen to the lungs. If not caught quickly, it can cause the lung to die because of the lack of oxygen.

In rare cases, a pulmonary embolism can be caused by air bubbles, part of a tumor, collagen or fat from the marrow of a broken bone when this substance blocks the pulmonary artery.

Risk factors for pulmonary embolism

Although anyone can develop a pulmonary ebolism, there are several risk factors that increase your likelihood of developing the condition.

Factors or medical conditions include:

  • Age — your risk of developing a pulmonary embolism increases as you age.
  • Family history — if you have a family history of a pulmonary embolism, you are at higher risk of developing one as well. 
  • Heart disease — people who suffer from cardiovascular disease are at higher risk of developing a pulmonary embolism. 
  • Cancer — cancers such as ovarian, lung and pancreatic increase the levels of substances in the blood that causes it to clot, making a PE more likely to occur. 
  • Prior surgeries — patients are often prescribed blood thinning medications prior to surgery to prevent blood clots after the procedure. 
  • Prolonged periods of inactivity — people who have extended periods of inactivity or spend an extended amount of time in a car or plane while traveling are more likely to develop blood clots. 
  • Pregnancy — pregnancy increases the pressure on the veins in the pelvis, which can slow the blood flow and lead to blood clots in the legs. 
  • Smoking — when combined with other risk factors, smoking can increase your risk of developing a PE. 
  • Obesity — people who are overweight or obese are more likely to develop a PE, especially if combined with other risk factors such as smoking or pregnancy.

Symptoms of pulmonary embolism

Symptoms of a pulmonary embolism vary from person to person.

Common symptoms include:

  • Shortness of breath — typically during exercise
  • Chest pain — sharp, stabbing pain that comes on quickly and worsens when you take a deep breath
  • Cough — dry or filled with blood
  • Sweating
  • Syncope
  • Anxiety
  • Fever
  • Lightheadedness — if you have a swollen arm or leg along with the symptoms above, you may have a blood clot.

Diagnosis of pulmonary embolism

A pulmonary embolism can be difficult to diagnose because other conditions have similar symptoms.

During a physical exam with your doctor, he or she will take a full medical history and order other tests such as:

  • Blood tests — checks for D dimer (a clot-dissolving substance), measure how much blood and carbon dioxide is in the blood or determine if you have a genetic blood clotting disorder
  • Electrocardiogram (EKG) — measures the electrical activity of the heart
  • Chest x-ray — takes pictures of the heart and lungs
  • Computerized tomography scan (CT) — shows lung or vessel abnormalities
  • Ultrasound in the legs — measures speed of blood flow

Treatment for pulmonary embolism

If you suspect you have a pulmonary embolism, it is critical to get to your doctor as soon as possible for evaluation. If your symptoms are severe, call 911 or go to the ER immediately.

The goal of treatment for a pulmonary embolism is to prevent the blood clot from increasing in size and new clots from forming. Treatments include:


First-line therapy for pulmonary embolisms are anticoagulants (blood thinners). If the clot(s) are severe, an anticoagulant such as Heparin that is given via IV or injected under the skin is used to break up clots and prevent new clots from forming. Warfarin is an oral anticoagulant that can treat less severe blood clots. Your doctor may also prescribe a novel oral anticoagulant, a newer class of blood thinner medication. These medications treat blot clots quickly and can be given orally.

Thrombolytics are clot-busting medications that are typically only used in the most severe cases due to an increased risk of severe bleeding.

Patients typically will take medications for up to three months after the pulmonary embolism.

Surgical procedures

If medications are not effective in preventing blood clots or busting current clots, surgical procedures may be necessary.

Procedures include:

Clot removal
In severe cases, your doctor can remove the clot using a catheter threaded through the vessels.

Vena cava filter
Some patients may need a vena cava filter inserted into the body’s main vein (inferior vena cava). A vena cava filter can prevent clots from reaching the lungs. Patients who are not candidates for anticoagulant medications or the medications do not work quickly enough are candidates for this medical procedure.

Recovery from pulmonary embolism

Prevention is key to preventing future pulmonary embolisms. Preventive measures you can take to prevent pulmonary embolisms include:

  • Taking blood thinners before and after surgery
  • Wear compression stockings, especially during long trips or periods of inactivity
  • Elevate legs when resting
  • Move around as soon as you can after surgery

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