Pulmonary embolism is a blockage in one of the pulmonary arteries in your lungs. In most cases, pulmonary embolism is caused by blood clots that travel to the lungs from the legs or, rarely, other parts of the body (deep vein thrombosis).
Because pulmonary embolism almost always occurs in conjunction with deep vein thrombosis, most doctors refer to the two conditions together as venous thromboembolism.
Although anyone can develop deep vein thrombosis (DVT) and pulmonary embolism, factors such as immobility, cancer and surgery increase your risk.
Pulmonary embolism can be life-threatening, but prompt treatment can greatly reduce the risk of death. Taking measures to prevent blood clots in your legs will help protect you against pulmonary embolism.
Pulmonary embolism occurs when a clump of material, most often a blood clot, gets wedged into an artery in your lungs. These blood clots most commonly originate in the deep veins of your legs, but they can also come from other parts of your body. This condition is known as deep vein thrombosis (DVT).
Occasionally, substances other than blood clots can form blockages within the blood vessels inside your lungs. Examples include:
- Fat from within the marrow of a broken long bone
- Part of a tumor
- Air bubbles
It’s rare to have a single pulmonary embolism. In most cases, multiple clots are involved but not necessarily all at once. The portions of lung tissue served by each blocked artery are robbed of blood and may die. This is known as pulmonary infarction. This makes it more difficult for your lungs to provide oxygen to the rest of your body.
Pulmonary embolism symptoms can vary greatly, depending on how much of your lung is involved, the size of the clots and your overall health — especially the presence or absence of underlying lung disease or heart disease.
Common signs and symptoms include:
- Shortness of breath. This symptom typically appears suddenly and always gets worse with exertion.
- Chest pain. You may feel like you’re having a heart attack. The pain may become worse when you breathe deeply (pleurisy), cough, eat, bend or stoop. The pain will get worse with exertion but won’t go away when you rest.
- Cough. The cough may produce bloody or blood-streaked sputum.
Other signs and symptoms that can occur with pulmonary embolism include:
- Leg pain or swelling, or both, usually in the calf
- Clammy or discolored skin (cyanosis)
- Excessive sweating
- Rapid or irregular heartbeat
- Lightheadedness or dizziness
When to see a doctor
Pulmonary embolism can be life-threatening. Seek immediate medical attention if you experience unexplained shortness of breath, chest pain or a cough that produces bloody sputum.