The Facts
An embolus is a particle that moves about in our blood vessels, either in
the veins or arteries. Most emboli are composed of clotted blood cells.
A blood clot is called a thrombus and a moving blood clot is called a
thromboembolus.
As an embolus moves through the body's blood vessels, it's likely to come
to a passage it can't fit through. It lodges there, backing up blood behind
it. The cells that normally get their blood supply via this passage are starved
of oxygen (ischemia) and die. This condition is called an embolism.
Types of Embolism
Pulmonary embolism: This condition is most common in women. An embolus, usually formed in the leg, lodges in one
of the arteries of the lungs.
Brain embolism: If a blood clot travels to the brain, this causes an
ischemic stroke or TIA (transient ischemic attack).
Retinal embolism: Small clots that wouldn't block a major artery can
block the smaller blood vessels feeding the retina at the back of the
eye. The result is usually sudden blindness in one eye.
Amniotic embolism: Not all emboli are made of clotted blood. In pregnancy,
the womb is filled with amniotic fluid, which protects the fetus. Amniotic fluid
can embolize and reach the lungs, causing pulmonary amniotic embolism.
Air embolism: Scuba divers who rise to the surface too rapidly can
generate air embolism, bubbles in the blood that can block arterial blood flow.