Definition
Deep venous thrombosis is a condition in which a blood clot forms in a vein that is deep inside the body.
Causes
Deep venous thrombosis (DVT) mainly affects the large veins in the lower leg and thigh. The clot can block blood flow. If the clot breaks off and moves through the bloodstream, it can get stuck in the brain, lungs, heart, or other area, leading to severe damage.
Risks for DVT include:
- Immobility which causes blood flow in the veins to be slow. Slow flowing blood is more likely to clot than normal flowing blood.
- A surgical operation which lasts more than 30 minutes is the most common cause of a DVT. The legs become still when you are under anaesthetic. Blood flow in the leg veins can become very slow.
- Any illness or injury that causes immobility increases the risk of a DVT.
- Long journeys by plane, train, etc are thought to cause a slightly increased risk of DVT. This is probably due to sitting cramped for long periods.
- Faulty blood clotting is an uncommon cause. One example is an inherited condition that causes the blood to clot more easily than normal (factor V leiden).
- The contraceptive pill and hormone replacement therapy (HRT) which contain oestrogen can cause the blood to clot slightly more easily. Women taking ‘the pill’ or ‘HRT’ have a small increased risk of DVT.
- Damage to the inside lining of the vein increases the risk of a blood clot forming. For example, a DVT may damage the lining of the vein. So, if you have already had a DVT, then you have a higher than average risk of having another one sometime in the future.
- Older people are more likely to have a DVT, particularly if you have poor mobility or have a serious illness such as cancer.
- Pregnancy increases the risk. About 1 in 1000 pregnant women have a DVT.
- Obesity also increases the risk of having a DVT.
- Bedrest
- Cigarette smoking
- Fractures
- Giving birth within the last 6 months Continue reading »























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