What causes an embolism?

A foreign body is any object or substance which shouldn't be in your blood. Foreign bodies that cause embolisms are known as emboli a single emboli is called an embolus.

Blood clots

Blood contains natural clotting agentswhich help prevent excessive bleeding when you cut yourself.

Certain health conditions such as obesity , heart disease, cancer or pregnancy can cause blood clots to form even where there's no bleeding. A clot can travel in the bloodstream before being deposited in an organ or limb.

Deep vein thrombosis (DVT) , a blood clot in the deep veins of your leg, is one of the main causes of pulmonary embolisms.


A fracture to a long bone, such as a thigh bone, can lead to fat particles within the bone being released into the bloodstream. They can also sometimes develop following severe burns or as a complication of bone surgery.


Embolisms can also occur if air bubblesor other gases enter the bloodstream.

Air embolisms are a particular concern for scuba divers. If a diver swims to the surface too quickly, the change in pressure can cause nitrogen bubbles to develop in their bloodstream. This can cause decompression sickness, which is often referred to as "the bends".

This could lead to breathing problems, a drop in blood pressure and loss of consciousness.

Content supplied by the NHS Website

Medically Reviewed by a doctor on 21 Dec 2018