Causes

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 come from the deep veins of your legs, a condition known as deep vein thrombosis (DVT).

In many cases, multiple clots are involved in pulmonary embolism. The portions of lung 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.

Occasionally, blockages in the blood vessels are caused by substances other than blood clots, such as:

• Fat from the marrow of a broken long bone
• Part of a tumor
• Air bubbles