Deep Vein Thrombosis
DVT Definition (Deep Vein Thrombosis)
DVT is a disease of the circulation, often associated with air travel. The medical term for a DVT is a venous thromboembolism. Our blood needs to be able to clot in order to provide the necessary protection for the body against severe loss of blood from an injury to a vein or an artery. However, blood can sometimes form clots whilst inside a blood vessel, which is the definition of a Deep Vein Thrombosis (DVT).
What causes DVT?
DVT causes can be many and varied. Blood flow through the deepest veins in the legs is relatively slow. This presents an increased risk of a solid clot forming, which can cause a partial or complete blockage in the vein. Although Deep Vein Thrombosis (DVT) can sometimes occur spontaneously in normal veins, without any obvious underlying cause, the risk of developing DVT is increased by the following surprisingly high numbers of risk factors :-
* Inactivity or Immobility
* Previous blood clots or DVT in the leg, or vein damage
* Medical and genetic conditions
* Major Surgery
* Broken leg
* Pregnancy
* Contraceptive pill use
* Hormone replacement therapy (HRT)
* Obesity
* Smoking
* Age – over 40 years
* Cancer
* Varicose veins
* Family history of DVT
* Paralysis
* Air travel
DVT Symptoms
Quite often there are no Deep Vein Thrombosis symptoms at the onset of the condition, although where they do appear, they may develop rapidly. The problem may only become apparent when a crisis develops into a medical emergency, and the blood clot reaches the lungs, where it becomes what is known as a pulmonary embolism. A DVT usually, although not always, affects only one leg. The thrombosis symptoms of a DVT in the leg include:-
* swelling – suddenly and in one leg
* pain in the leg
* warm skin
* tenderness
* redness, particularly at the back of the leg, below the knee.
Occasionally some of the surface veins become more visible through the skin, and there may also be some pain on flexing the foot upwards.
How is DVT diagnosed?
There can be many causes of a painful or swollen leg, which means that it can be difficult for a doctor to successfully perform a first time DVT diagnosis. If you have some of the DVT risk factors listed above, and your doctor suspects that you may have a DVT, they will usually recommend that you have some urgent tests performed, which will normally be carried out in a hospital, or possibly a specialist anti-coagulation clinic.
DVTs are usually detected by ultrasound, which is capable of detecting even the smallest blood clots. If a doctor suspects a DVT he or she will usually request an urgent ultrasound test, and a follow-up blood test. There is a special blood test known as the D-dimer test, which is capable of detecting fragments of a blood clot that have broken up, and present within the blood stream. This gives a reliable indication that a person may have developed a DVT.
If the results of an Ultrasound and D-dimer test cannot confirm a diagnosis of DVT, a venogram might be used. This is a more detailed test that involves a contrast dye being injected into the vein in your leg. An X-ray is then used to see whether the dye is flowing through your vein, or if it is blocked by a blood clot.
Is DVT dangerous?
DVTs themselves are not dangerous, but they are associated with complications which can become life threatening, or prove fatal. The most common serious complication is a pulmonary embolism, which occurs in approximately 30% of cases of DVT. This is where a part of the blood clot in the leg vein breaks off and travels through the blood stream to the lung, where it becomes lodged, causing chest pain and severe breathing difficulties.
Pulmonary embolism, is a common cause of sudden, unexpected death. A severe pulmonary embolism can cause the lungs to collapse, and result in heart failure. If left untreated, 10% of people die from pulmonary embolism.
More rarely, a part of the clot may also lodge in other organs including the brain, where it can lead to a stroke.
Deep Vein Thrombosis Treatments
Two thirds of people diagnosed with a DVT require initial treatment at a hospital, or possibly an anticoagulation clinic. The aim of the DVT treatment is to dissolve the blood clot and prevent further clots from forming. The primary DVT therapy is with anticoagulant medicines such as Heparin or Warfarin which thin the blood, allowing it to flow more freely. Inactivity and bed rest is discouraged and patients are encouraged to move around as much as possible. Regular blood tests are performed monitor the effectiveness of the treatment and to reduce the risk of a haemorrhage.
Painkillers and heat applied to the area may also be advised for relief of symptoms of a DVT, and compression stockings are often worn to cover the length of the whole leg to give support to the veins and reduce swelling.
As well as wearing compression stockings, you may be advised to raise your leg while you are resting, as this helps to reduce the pressure in the veins of the leg, and also helps tp prevent blood and fluid from gathering in the leg.
Occasionally a doctor may recommend dvt surgery to remove a deep vein clot. The procedure is called venous thrombectomy. This is usually necessary only in the case of a severe form of DVT called phlegmasia cerulea dolens, which does not respond to the non-surgical treatments described above. Phlegmasia cerulea dolens, if not adequately treated, can cause gangrene, which is when the tissues do not receive sufficient oxygen, and subsequently die. Gangrene is a very serious condition that may result in the amputation of the affected limb.
It should be noted that Aspirin is not used to prevent DVT. (Aspirin is widely used to help prevent blood clots in arteries which can cause strokes and heart attacks. However, aspirin does not seem to be very effective at preventing blood clots in veins.)
DVT Prevention – How to avoid getting a DVT, especially when travelling by Air
Prophylaxis is a medical term used for ‘prevention’. DVT prophylaxis is always preferable than having to deal with consequences of developing the condition. There are certain precautions that you can take to avoid getting a DVT.
If possible, avoid long periods of immobility such as sitting in a chair for many hours to avoid the blood ‘pooling’, and to get the circulation in the legs moving.
Major surgical operations are known to be a risk for a DVT – particularly operations to the hip, lower abdomen, and leg. You may be given an anticoagulant such as a heparin injection just before having an operation to help prevent a DVT. An inflatable sleeve connected to a pump to compress the legs during a long operation may also be used. It is also common practice to get you up and walking as soon as possible after an operation.
If you are planning to travel by air, especially on a long-haul flight, the the following specific tips can significantly reduce your chances of developing a flight or travel related DVT :-
* drink plenty of water
* avoid excessive alcohol as it can lead to dehydration
* avoid taking sleeping pills as it can cause immobility
* perform simple leg exercises, such as regularly flexing your ankles. Most airlines provide information on suitable exercises to do during your flight
* take occasional short walks, when in-flight advice suggests it is safe to do so
* take advantage of refuelling stopovers where it may be possible to get off the plane and walk about
* wear elastic compression stockings.
After DVT
After a DVT has been diagnosed, persistent symptoms may occur in the affected part of the leg. In order to minimise the risk of further complications you may be advised to wear a compression stocking for many months or even years. Also, by following some simple additional steps, you can further minimise the possibility of longer term problems as follows :-
* Raise your leg when you are resting to reduce the pressure in the veins in the affected leg.
* Raise the lower end of your bed by a few inches so that your foot and calf are slightly higher than your hip whilst you are sleeping.
