A deep vein thrombosis (DVT) occurs when a blood clot forms in a vein. A DVT usually develops in the calf, but it sometimes also occurs in the thigh, and occasionally in other deep veins in your body.
Some of the common symptoms of a DVT are:
- Tenderness in the leg
- Swelling and a feeling of tightness, the skin may feel stretched
- However some DVTs have no symptoms at all (asymptomatic)
What causes a DVT?Immobility
Journeys, by any means of transport, where you sit still for long periods of time without being able to stretch your legs or move about. A medical condition or injury that restricts normal movement or activity.
Surgery or illness
Undergoing surgery may mean lying still for long periods of time. Staying in hospital as a medical patient may also involve long periods of imobility. Having some treatments such as chemotherapy, which may damage veins, can also increase your risk.
Some people have genetic conditions, such as Factor Five Leiden, which will increase their risk of a deep vein thrombosis.
If you have already had a DVT then there may be some vein damage and you will be at a higher risk.
Contraceptive pill and hormone replacement therapy (HRT)
Both contraceptive pills and HRT therapy normally contain the hormone oestrogen. For some people, this can make their blood more likely to clot easily.
Approximately 1 in 1000 pregnant women will have a DVT.
Other reasonsIllustration: inside a vein
There has recently been some speculation that sitting at your desk for long periods of time may also be an increased risk for DVT.
It should also be noted that some people will have a DVT for no apparent reason.
Diagnosing a DVT
It can be difficult to diagnose a DVT as there may be many causes for a swollen and painful leg. However there are tests that can detect clots. The following three tests are often used.
- D-dimer test
- Ultrasound scan
It is essential to treat a DVT as quickly as possible to prevent the clot getting bigger or pieces of it breaking off and travelling to the lungs causing a pulmonary embolism.
Heparin and warfarin are the two anticoagulants that are normally used to treat DVT. Anticoagulant therapy is often referred to as "thinning the blood". However it does not thin the blood but lengthens the time it takes for your blood to clot. This prevents clots for forming so easily. See the page Anticoagulation therapy.
Wearing compression stockings may help to prevent further damage. They can also help to reduce pain and can also help stop post-thrombotic syndrome occurring. Post-thrombotic syndrome is damage to the tissues of your calf. It can cause pain and a rash. Leg ulcers may also occur.
Compression stockings need to fit properly and you will need to be measured by your health care professional (HCP). They should be worn every day. Your HCP will tell you how long you will need to wear them for.
Helping you to avoid a DVTIMPORTANT: The following suggestions apply for any long journey, such as coach, train or car, and also when sitting for any lengthy period.
- Keep your legs and feet active - every half hour, bend and straighten them to keep the blood circulating
- Press down on the balls of your feet, then raise the heels to help increase the blood flow in your legs
- Don't cross your legs
- Exercise your chest and upper body frequently
- Do deep breathing exercises to help improve circulation
- Walk up and down the aisles frequently
- If you are on a long flight, which has refuelling stops, take the opportunity to leave the plane and walk about
- Drink plenty of water - preferably a glass every hour
- Avoid alcohol - or, if you must, take only small amounts. Alcohol will cause dehydration and sleepiness
- Avoid sleeping pills - they will cause you to be immobile for long periods
- Try not to sleep for too long in a cramped position - move about as much as possible, and stretch out
- Make sure you have had plenty of rest before you make a lengthy journey, so that you are not too tired