Pulmonary Embolism (cont.)
What causes pulmonary embolism?
Major Causes
In 9 out of 10 cases, pulmonary embolism (PE) begins as a blood clot in the
deep veins of the leg (a condition known as
deep vein thrombosis). The clot
breaks free from the vein and travels through the bloodstream to the lungs,
where it can block an artery.
Clots in the leg can form when blood flow is restricted and slows down. This
can happen when you don't move around for long periods of time, such as:
- After some types of surgeries
- During a long trip in a car or on an airplane
- If you must stay in bed for an extended time
Veins damaged from surgery or injured in other ways are more prone to blood
clots.
Other causes
Rarely, an air bubble, part of a tumor, or other tissue travels to the lungs
and causes pulmonary embolism. Also, when a large bone in the body (such as the thigh bone)
breaks, fat from the marrow inside the bone can travel through the blood to the
lungs and cause pulmonary embolism.
Who is at risk for pulmonary embolism?
Populations affected
Pulmonary embolism (PE) occurs equally in men and women. Risk increases with
age: For each 10 years after age 60, the risk of pulmonary embolism doubles.
Certain inherited conditions, such as factor V Leiden, increase the risk of
blood clotting, and, therefore, the risk of pulmonary embolism.
Major risk factors
People at high risk for a blood clot that travels to the lungs are those who:
- Have deep vein thrombosis (DVT, a blood clot in the leg) or a history of
DVT
- Have had pulmonary embolism before
Other risk factors
People who recently have been treated for cancer or who have a central venous
catheter (a tube placed in a vein to allow easy access to the bloodstream for
medical treatment) are more likely to develop DVT. The same is true for people
who have been bedridden or have had surgery or suffered a
broken bone in the
past few weeks.
Other risk factors for DVT, which can lead to pulmonary embolism, include
sitting for long periods of time (such as on long car or airplane rides),
pregnancy and the 6-week period after pregnancy, and being overweight or
obese.
Women who take hormone therapy or
birth control pills also are at increased risk
for DVT.
People with more than one risk factor are at higher risk for blood clots.
Next: What are the signs and symptoms of pulmonary embolism? »
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