Embolism 

Introduction 

Types of embolism

There are three types of embolism, which are briefly described below.

Cerebral embolisms are caused when a foreign body – usually a blood clot – blocks the blood supply to the brain. They are the leading cause of stroke.

Pulmonary embolisms occur when a foreign body blocks the artery that transports blood to the lungs. Many cases are caused by a clot – formed as the result of a condition called deep vein thrombosis (DVT) – travelling from a leg to the lungs. 

Amniotic fluid embolisms occur very rarely. They are caused by amniotic fluid – the fluid that surrounds and protects a baby inside the womb – leaking out of the womb into the mother's blood vessels during labour, blocking the vessels. The mother may then develop breathing problems, a drop in blood pressure and loss of consciousness.

An embolism is a condition where the blood flow in an artery is blocked by a foreign body, such as a blood clot or an air bubble.

To function properly, the body's tissues and organs need oxygen, which is transported around the body in the bloodstream. If the blood supply to a major organ – such as the brain, heart or lungs – is blocked, the organ will fail (lose some or all of its function).

Two of the most serious conditions that can be caused by an embolism are:

  • stroke, where the supply of blood to the brain is interrupted or completely cut off
  • pulmonary embolism, where the blood supply to the lungs is cut off

Embolisms are a common health problem, and are a major cause of disability and death in the UK and across the world. For example, in England each year it's estimated there are 41,000 pulmonary embolisms and 120,000 strokes caused by embolisms.

What causes an embolism?

A foreign body is any object or substance that shouldn't be present 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 agents that 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.

Fat

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.

Air

Embolisms can also occur if air bubbles or 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".

See air embolism for more information.

Cholesterol

In people who have extensive atherosclerosis (narrowed arteries due to a build-up of cholesterol), small pieces of cholesterol can sometimes break away from the side of a blood vessel, resulting in an embolism.

Increased risk

Things that can increase your risk of an embolism include:

Treating embolisms

How an embolism is treated will depend on:

  • what caused the blockage
  • the size of the blockage
  • where in the body the blockage is

A surgical procedure called an embolectomy is sometimes carried out to remove an obstruction. During this operation, the surgeon will make a cut in the affected artery and the foreign body causing the blockage will be sucked out in a process known as aspiration.

Medication may be used to dissolve embolisms (thrombolysis) caused by blood clots. Anticoagulant medication, such as warfarin, heparin and low-dose aspirin, can help make the blood less sticky and stop further clots forming.

Embolisms caused by air bubbles are usually treated in a hyperbaric chamber. The air pressure inside the chamber is higher than the normal air pressure outside, which helps reduce the size of the air bubbles inside the diver's body.

Read more about treating air embolisms.

Prevention

It's not possible to prevent all embolisms, but you can take steps to significantly reduce your risk. These steps include:

  • eating a healthy diet that is low in fat, high in fibre and includes whole grains and plenty of fresh fruit and vegetables (at least five portions a day
  • limiting the amount of salt in your diet to no more than 6g (0.2oz or 1 teaspoon) a day
  • losing weight if you're overweight or obese, using a combination of regular exercise and a calorie-controlled diet 
  • stopping smoking, if you smoke
  • exercising for a minimum of 150 minutes a week 

Page last reviewed: 22/01/2013

Next review due: 22/01/2015

Ratings

How helpful is this page?

Average rating

Based on 159 ratings

All ratings

Add your rating

Comments

'I got DVT from flying'

Mark Pownall developed deep vein thrombosis (DVT) on a long-haul flight from New Orleans to London

Love your heart

Poor diet, lack of exercise and smoking are the main offenders behind the UK's high level of deaths from heart disease