Thrombosis

Introduction 

Blood platelets clotting

Thrombosis of deep leg veins causes swelling, redness and pain in the leg

Thrombosis is the clotting of blood within a blood vessel. It occurs when a blood clot blocks a vein or an artery, obstructing or stopping the flow of blood.

Types of thrombosis

Thrombosis can occur anywhere in the body’s bloodstream. There are two main types of thrombosis:

  • venous thrombosis, which is a blood clot that develops in a vein, and
  • arterial thrombosis, which is a blood clot that develops in an artery.

One of the most common types of venous thrombosis is deep vein thrombosis (DVT), which is a blood clot in one of the deep veins of the body.

Arterial thrombosis often occurs in arteries that supply the heart, resulting in a heart attack. It can also occur in the arteries of the brain, causing a stroke.

Sometimes a blood clot (or part of one) can come away from its original site and travel through the bloodstream. If this occurs, the clot can become lodged in another part of the body. This is known as an embolism. A blood clot that lodges in one of the lungs is called a pulmonary embolism.

Who is affected by thrombosis?

Thrombosis is a widespread condition and a leading cause of death in the UK. Every year, one in every 1,000 people in the UK is affected by venous thrombosis.

Anyone can be affected by thrombosis, although it usually develops in older people and becomes more common with age. As well as age, there are a number of other factors that make developing thrombosis more likely, including:

  • family history,
  • inactivity, and
  • obesity.

Thrombosis often has few or no symptoms, and is sometimes referred to as a silent condition. Therefore, it is important to be aware of the signs and risk factors of thrombosis. There are several things that you can do to help prevent the condition occurring.

  • show glossary terms
Blood
Blood supplies oxygen to the body and removes carbon dioxide. It is pumped around the body by the heart.
Vein
Veins are blood vessels that carry blood from the rest of the body back to the heart.
Arteries
Arteries are blood vessels that carry blood from the heart to the rest of the body.
Pain
Pain is an unpleasant physical or emotional feeling that your body produces as a warning that it's been damaged.
Kidneys
Kidneys are a pair of bean-shaped organs located at the back of the abdomen. They remove waste and extra fluid from the blood and pass them out of the body as urine.
Swelling
Inflammation is the body's response to infection, irritation or injury. It causes redness, swelling, pain and sometimes a feeling of heat in the affected area.
Lungs
Lungs are a pair of organs in the chest that control breathing. They remove carbon dioxide from the blood and replace it with oxygen.
Embolism
An embolism is the sudden blockage of a blood vessel, usually by a blood clot or air bubble.
Intravenous
Intravenous (IV) means the injection of blood, drugs or fluids into the bloodstream through a vein.

Last reviewed: 06/10/2008

Next review due: 06/10/2010

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