Lungs Home > Cause of Pulmonary Embolism
The most common pulmonary embolism cause is deep vein thrombosis. Deep vein thrombosis is a blood clot that forms in a vein, deep in the body. Pulmonary embolism occurs when a blood clot in the vein breaks off, travels through the bloodstream, and travels to the lungs. In rare cases, an air bubble, a part of a tumor, or other tissue travels to the lung can also lead to pulmonary embolism.
In 9 out of 10 cases, pulmonary embolism is caused by deep vein thrombosis (DVT). DVT is a blood clot that forms in a vein, deep in the body. Pulmonary embolism occurs when the blood clot in a vein breaks off, travels through the bloodstream, and travels to the lungs.
(Click Deep Vein Thrombosis for more information about DVT.)
Leg clots can form when blood flow is restricted and slows down. This occurs when you do not 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 period of time.
Veins that are damaged from surgery, or veins that are injured in other ways, are more prone to blood clots. In rare cases, an air bubble, a part of a tumor, or other tissue travels to the lung and causes pulmonary embolism.
People who are at the greatest risk for pulmonary embolism are those who:
- Have DVT
- Have previously had DVT
- Have previously had a pulmonary embolism.
Pulmonary embolism occurs equally in men and women, and your risk for pulmonary embolism doubles every 10 years after age 60. Preventing pulmonary embolism begins with preventing DVT. It is important to know if you are at risk for DVT and to take steps to lower your risk.
DVT risk factors include:
- Inherited conditions that cause increased risk for blood clotting
- Restricted or slow blood flow in a deep vein due to injury, surgery, or having to stay in bed for a long time
- Cancer and its treatment
- Medical conditions such as varicose veins
- Sitting for a long period of time, such as on long trips in a car or on an airplane (see DVT and Travel)
- During pregnancy and in the six-week period after delivery
- Being over age 60 (although DVT can occur at any age)
- Being overweight or obese (see BMI Calculator to find out if your weight is within a healthy range)
- Taking birth control pills or hormone replacement pills
- Having a medical condition that requires a central venous catheter (a central venous catheter is a tube placed in a vein to allow easy access to your bloodstream for medical treatment).
Your risk for deep vein thrombosis and pulmonary embolism will increase if you have several DVT risk factors at the same time.