Thrombosis Australia

Thrombosis Australia is a central information and resource hub for the community proudly brought to you by the Perth Blood Institute



Our Thrombosis Australia Advisory Panel consists of eminent Australian healthcare professionals.

Thrombosis Australia Advisory Panel

If you are a healthcare professional you can access the Thrombosis Australia Professionals site here:

Thrombosis Australia Professionals


Every year 30,000 Australians develop thrombosis(1, 2), including deep vein thrombosis (DVT) and pulmonary embolism (PE), costing the Australian health system $3.8 billion per year in today's value(3). Blood clots are responsible for the top three cardiovascular killers: stroke, heart attack, and VTE.

In Australia:

  • there is one stroke every 10 minutes.
  • an average of 21 Australians die from a heart attack each day.(4)
  • blood clots are responsible for an estimated 10% of all deaths in Australia, and yet up to 70% of these are preventable(5).

Many of the risk factors for thrombosis are preventable given sufficient awareness and healthcare priority. Therefore, it is a significant problem that many Australians underestimate the danger of blood clots.

Help fund our thrombosis research

We invite you to get involved in our fight against thrombosis by participating in an upcoming event, donating to our cause, or partnering with us. Get involved today. 


Thrombosis is the formation of a blood clot (or “thrombus”) in a blood vessel. Our body contains many blood vessels which provide the body with a constant supply of oxygen and nutrients which are carried in the blood.

Normal clot formation:

A healthy blood stream exists in a delicate balance. Blood is required to flow freely so that the entire body can receive adequate amounts of oxygen. Therefore, any blockages occurring in blood vessels can be highly dangerous. However, the ability for blood to clot is also important in order to stop excessive bleeding in the case of an injury. For example - at the site of a cut, a blood clot forms and “plugs up” the wound to stop bleeding.  

Dangerous clot formation:

In most people, this delicate balance is maintained, and the clotting mechanism is under tight control. However, certain conditions and circumstances can undermine the balance and cause the clotting mechanism to be over- or under-activated. This can result in severe complications including strokes.


A blood clot in a vein is known as a venous thrombosis. An example of this is deep vein thrombosis (DVT) where a blood clot forms in the deep veins of the leg.

A blood clot that forms in an artery is known as an arterial thrombosis. An example of this is a blood clot in the artery of the heart which can lead to myocardial infarction (a heart attack), or a stroke when it forms in the brain.

An embolism is when the blood clot detaches or “breaks off” from the blood vessel and travels around the body through the blood stream. When this happens, the clot is known as an embolus. An example of this is a pulmonary embolism (PE) where a blood clot from a deep vein thrombosis has broken off and traveled to the lung where it becomes lodged in the pulmonary artery.

For more information on DVT and PE see: What are DVT and PE?


There are many risk factors for thrombosis which are important to be aware of to avoid and prevent thrombosis.

Being unable to move around:

  • Hospitalisation
  • Long-term bed rest
  • Paralysis
  • Long-term sitting - such as travel

Surgery and Injury:

  • Major injury - especially of the legs and lower body
  • Major surgery - especially of hips and legs
  • Catheterisation

Other medical conditions:

  • Cancer and cancer treatment
  • Heart failure or heart disease
  • Thrombophilia (clotting disorder)
  • Obesity/overweight


  • Birth control which contains oestrogen
  • Hormone replacement therapy
  • Pregnancy and the 6 weeks following birth


  • Smoking
  • Family history of thrombosis
  • Age over 50 years
  • Varicose veins

If any of these risk factors apply to you it is important to discuss this with your doctor.


You can lower your risk of developing thrombosis with the following actions:

  • If you are concerned or display the symptoms of DVT or PE, consult your doctor.
    • Especially if you are on birth control, hormone replacement therapy, or are pregnant or have recently given birth.
  • Ask your doctor about medication or compression stockings during hospital stays and long flights.
  • Maintain a healthy weight.
  • Exercise regularly and stay active – moderate exercise is okay.
  • Avoid long periods of staying still by walking around or stretching intermittently.
  • Stretch and perform simple leg and foot exercises if you cannot walk around.
  • Stop regularly (every 2 hours or so) on long drives and move around.
  • Stay hydrated.
  • Wear loose fitting clothing during travel.
  • Avoid stress – attempt stress-reducing activities such as meditation or breathing exercises.


What is a blood clot?

A blood clot or “thrombus” is a plug that forms in the blood to stop the bleeding from a wound. It is only a problem if the body forms blood clots when it doesn’t need to – which can lead to complications such as deep vein thrombosis (DVT, pulmonary embolism (PE) and cardio-embolic stroke.

What is a deep vein thrombosis (DVT)?

A DVT is a blood clot that has formed in the deep veins of your body – usually in your calves or upper legs.

What is a pulmonary embolism (PE)?

A PE occurs when a blood clot breaks off from the wall of the vein and travels to your lungs, causing a blockage.

What is the relationship between a DVT and a PE?

PE is often caused by a DVT detaching from a blood vessel, travelling through the blood stream, and becoming lodged in your lung.

Are men or women more likely to develop a blood clot?

The risk is more or less equal between men and women – but women are more at risk if they are taking a combined oral contraceptive or are pregnant.

What is the rate of death in people who have a PE?

This is dependent on many factors including age, health, and underlying conditions.

What can I do to minimise my risk of a first-time or recurrent DVT?

Staying active and maintaining a healthy weight, staying hydrated, eating a healthy diet, avoiding immobility, and avoiding stress can all help to reduce the risk of a DVT.  

What are anticoagulants?

They are medicines in the form of tablets or injections that are given to significantly reduce the risk of blood clots.

What are the risks associated with anticoagulants?

Excessive bleeding or internal haemorrhage are more likely when taking an anticoagulant. Ask your doctor about any modifications to your lifestyle or other medicines before starting anticoagulants.  If you are on anticoagulants tell your doctor if there are any signs of bleeding, or your health professional before changing to other medication, or prior to surgical procedures.                   

Learn more about thrombosis.

Download a leaflet version of this page to keep or give to a loved one.

Help fund our thrombosis research.

We invite you to get involved in our fight against thrombosis by participating in an upcoming event, donating to our cause, or partnering with us. Get involved today.                        

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  1. Ho WK, Hankey GJ, Eikelboom JW. The incidence of venous thromboembolism: a prospective, community-based study in Perth, Western Australia. Med J Aust. 2008;189(3):144-7.
  2. Szabo F, Marshall C, Huynh DK. Venous thromboembolism in tropical Australia and in Indigenous Australians. Semin Thromb Hemost. 2014;40(7):736-40. Epub 2014/10/04.
  3. Access Economics Pty Ltd for the Australia and New Zealand working party on the management and prevention of venous thromboembolism. The burden of venous thromboembolism in Australia, 1 May 2008. Access Economics Pty Ltd; 2008.
  4. The Heart Foundation:
  5. Guyatt GH, Akl EA, Crowther M, et al. Antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest 2012;141:7S–47S
  6. Centre for Disease Control and Prevention (CDC). Venous Thromboembolism: Impact of Blood Clots on the United States.
  7. Smith S, Travers R, Morissery J. How it all starts: Initiation of the clotting cascade. Crit Rev Biochem Mol Biol. 2015; 50(4):326-336.
  8. Oklu R. Thrombosis. Cardiovasc Diagn Ther. 2017;7:S131-S133.
  9. Queensland Health. Guideline for the Prevention of Venous Thromboembolism (VTE) in Adult Hospitalised Patients. 2018.