An embolism occurs when foreign material, such as a blood clot or air bubble, travels through the bloodstream and becomes lodged in a blood vessel, blocking the flow of blood. Embolisms can occur in veins, which carry oxygen-poor blood back to the heart and lungs, as well as arteries, which carry oxygen-rich blood from the heart to the tissues of the body. Depending on the size of the embolism and which blood vessel it is obstructing, the result can range from a complete lack of symptoms to a life-threatening emergency.

Embolisms are usually described by either the type of material that is involved, such as air or fat, or the vessel that is obstructed, such as the pulmonary artery. The most common type is a thromboembolism, which is caused by a piece of a blood clot. This could lead to heart attack or stroke.

The tests used to diagnose an embolism depend on which type of embolism is suspected. Similarly, treatment will depend on which type of embolism is diagnosed. Treatment could include medications to dissolve the embolism or increase blood flow, surgery to remove the embolism or methods to prevent or treat risk factors for further emboli.