Deep Vein Thrombosis DVT » The British Vein Institute

Deep vein thrombosis » DVT

Deep Vein Thrombosis is a condition in which blood clots form in the deep veins of the leg. This may lead to swelling of the leg and is hazardous to life, because bits of clot in the leg may fall off and travel via the main veins to the heart. Here they pass through without a problem, but become stuck in the arteries to the lungs. This is called a 'pulmonary embolism'. This condition causes shortness of breath, collapse and chest pain. Left untreated this may lead to death.

Deep vein thrombosis occurs in about 1 person per thousand per year. It may cause no symptom, but more often leads to pain and swelling in the calf. If the clots spread to the thigh or to the groin both the thigh and calf become very swollen.

What causes deep vein thrombosis?

DVT occurs as a result of both inherited and environmental factors. There is a number of inherited conditions that cause DVT. Patients with this problem sometimes know of other family members, who have also suffered a DVT. Injuries to the leg, especially fractures, may cause a DVT. Orthopaedic surgeons, who look after patients with fractures look out for leg swelling after a fracture in case a DVT has developed. In fact, any treatment in hospital can lead to deep vein thrombosis. Operations on the leg, such as hip or knee replacement, can cause a DVT. Any general surgical treatment under general anaesthetic can lead to this problem.

General medical conditions, such as a heart attack or stroke may also lead to the development of a DVT. Any period of immobility may lead to the development of a DVT, especially in those, who have an inherited tendency to clotting, known as a 'thrombophilia'. This is best known, following long-haul air travel, but can also arise after long car and bus journeys. DVT after an extended period of travel is sometimes known as 'travellers' thrombosis'. It is thought, that the risk starts after a period of 4 hours of travel and increases as the duration of travel increases.

Diagnosis & treatment

DIAGNOSIS OF DEEP VEIN THROMBOSIS

Philip Coleridge Smith - British Vein Institute

A DVT should be suspected in someone, who has some of the factors mentioned above, and develops pain and swelling in the leg. This can range from very mild to very severe swelling of the leg. Chest symptoms, such as shortness of breath and chest pain in someone with a swollen leg, may suggest that pulmonary embolism has occurred. A suspected DVT is a medical emergency and requires immediate investigation and treatment.

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You should seek advice from your doctor, if pain and swelling arises in the leg. The tests needed to find out if you have a DVT include a blood test and ultrasound imaging, as well as clinical examination. In fact, clinical examination is very poor at proving or excluding a DVT and cannot be relied upon to provide a reliable answer. A blood test can be used to detect 'd-dimer' in the blood.

This chemical is released as blood clots form and can give an indication, that a DVT has occurred. However, raised d-dimer levels can occur even when there is no DVT, so the results of this test must always be checked by colour duplex ultrasound imaging. Ultrasound scanning gives images of the veins and measures blood flow. A DVT can readily be seen by an expert in this technique. There is pain and swelling in the leg. If no DVT can be found, then other possible reasons for pain in the leg can be sought, such as a large bruise or a tear in the muscle.
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TREATMENT OF DEEP VEIN THROMBOSIS

Once the diagnosis of deep vein thrombosis has been made or is suspected, then treatment should be started immediately. The DVT may get a lot worse or a pulmonary embolism may happen, if treatment is not given soon enough. The standard treatment is to commence anticoagulation with heparin injections. This drug is given by subcutaneous injections, usually given in the abdominal wall. The anticoagulant effect of this drug is fully established within half an hour of injection.

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A recent development is the use of 'direct oral anticoagulant' drugs (also known as 'DOACs') for the treatment of deep vein thrombosis. These achieve the same effect as heparin but can be taken by mouth once or twice per day. Examples of these drugs are rivaroxaban and apixaban. These drugs require no regular blood testing and the same dose is suitable for most people. They have largely replaced the used of the older anticoagulant drug, warfarin, for the management of venous thrombosis.

Anticoagulation usually has to be continued for 3 – 6 months following diagnosis of a DVT.

Warfarin treatment takes a week or more to become effective, and is used where more modern drugs are not thought to be appropriate. Blood tests need to be done regularly to adjust the dose of warfarin.
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After a deep vein thrombosis

In general, timely treatment of a DVT will lead to a full recovery with disappearance of the thrombus from the vein and restoration of normal blood flow. It is very unusual for a serious pulmonary embolism to occur, once anticoagulant treatment has been established. In some patients, veins are permanently damaged by a DVT with scarring, narrowing or permanent blocking of the vein. This can also lead to damage to the non-return valves in the veins, permitting blood to flow in the wrong direction, towards the feet. A 'post-thrombotic' syndrome can develop with pain and swelling in the leg, leading to damage to the skin at the ankle and ulceration of the leg. It is best to wear medical compression stockings for at least six months after a DVT to prevent this complication.

In the longer term, most people who have suffered a DVT, will recover completely. Most will have no further episodes, but there is a risk of another DVT arising. Anyone who has previously suffered a DVT, should take additional precautions to prevent a further episode at times of risk, such as when undergoing treatment in hospital or when undertaking long distance travel. Elastic compression stockings and anticoagulant drugs are usually used as preventive measures.

Deep Vein Thrombosis