What is deep vein thrombosis (DVT)?
Deep vein thrombosis (DVT) is a blood clot that occurs in a deep vein; that is, a vein that is not on the surface of the skin. DVT can occur anywhere, but is most often seen in the leg.
If you think you might have DVT, see a doctor. The most serious complication of DVT is pulmonary embolism, which is when a piece of the blood clot breaks off and lodges in the lung. This causes a serious illness and is potentially life-threatening.
What are the symptoms of deep vein thrombosis (DVT)?
The main signs and symptoms of DVT are pain and swelling in the affected area - usually your calf or thigh.
Some people have no signs or symptoms.
When to seek help
DVT is a serious condition, so if you think you may have DVT, you should see a doctor without delay.
Call an ambulance on triple zero (000) if you:
What causes DVT?
Anything that slows blood flow in deep veins can cause DVT.
People who have DVT may have:
- been in bed for long periods, such as when in hospital
- been inactive, such as during a long flight
- had major surgery recently
- had an injury, such as a fracture
- had a major illness such as cancer, heart failure or a serious infection
- been taking the oral contraceptive pill or hormone replacement therapy containing oestrogen
Women who are pregnant or who have recently had a baby are also at increased risk of DVT. So are people who are overweight, or who smoke.
DVT can also happen spontaneously, with no apparent cause. Some people with spontaneous DVTs have a genetic condition that makes their blood more likely to clot.
How is a DVT diagnosed?
To diagnose DVT, the doctor will need to talk to you about your symptoms and examine you to look for signs of DVT, such as swelling and pain.
After this, if your doctor thinks you may have DVT, they may suggest you have an ultrasound. A blood test called a D-dimer test can also be done to help detect blood clots. If the doctor thinks there is a risk that part of the blood clot has travelled to your lungs, they may order a chest CT scan.
How is DVT treated?
If you have DVT, you will be treated with medicine that reduces blood clotting (called anticoagulant medication). This can be given either as tablets or via injections and you will probably need to take it for several months.
In very severe cases, a medicine is used to break down the clot. The person normally needs to stay in hospital when this is given as it can cause bleeding.
You may also be asked to wear compression stockings to bring down the swelling.
What are the complications of a DVT?
Bits of the blood clot can break off and travel around the body, affecting the heart or lungs.
After having a DVT, the leg can remain swollen and ulcers may develop.
How is DVT prevented?
If you are travelling or are hospitalised, you can reduce your risk of developing DVT by wearing compression stockings, moving your feet and legs as much as possible, and drinking plenty of water.
If you have already had a DVT, it is very important to quit smoking, keep fit and maintain a healthy weight. Some people may need to stay on low-dose anticoagulant medication long-term or use it prior to long haul flights.
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Last reviewed: March 2021