Deep vein thrombosis (DVT)

DVT (deep vein thrombosis) is a serious condition in which a blood clot forms in the deep veins of the lower leg or calf and blocks blood flow. DVT can lead to leg swelling, redness, and pain, but it can also occur without these symptoms. DVT can become a life-threatening condition if the blood clot breaks loose from its original location in the vein and travels through the bloodstream into the lungs. This potentially fatal event is known as pulmonary embolism (PE). Here you can find more information on DVT in general and solutions for its prevention.

Deep vein thrombosis (DVT)

What is deep vein thrombosis?

Deep vein thrombosis (DVT) is a serious condition in which a blood clot forms in one or more of the deep veins. 

Illustration deep vein thrombisis
The symptoms of a DVT can go unrecognised.

What causes DVT?

Deep vein thrombosis is usually caused by a combination of different underlying conditions:

Restricted movement 

Blood flow in the veins is slowed down because of restricted movement for a long period of time (illness, after surgery, long-distance traveling).

Blood clots form more easily than normal

The risk of getting DVT is increased with a condition that causes blood to clot (coagulate) more easily than normal. Some of these conditions include:

  • cancer and cancer treatments
  • heart disease and lung disease
  • thrombophilia, a genetic condition where the blood has an increased tendency to clot

Infections or inflammation

Infections or inflammation can promote thrombus formation by affecting the lining surface of the vein, e.g. through vessel wall damage and increased coagulability.

Damaged blood vessels

If the wall of a blood vessel is damaged, it may become narrowed or blocked, which can cause a blood clot to form. Blood vessels can be damaged by injuries such as broken bones or severe muscle damage.


DVTs are rare in pregnancy, although pregnant women are 3 to 4 times more likely to develop thrombosis than non-pregnant women of the same age. A clot can form at any stage of pregnancy and up to six weeks after giving birth.

In addition, several risk factors for the development of DVT exist.

What are some potential complications of DVT?

About one of every two to three patients with previous DVT will develop a long-term complication known as post-thrombotic syndrome (PTS), despite optimal anticoagulant treatment. PTS is a progressive disease and it can show up as chronic pain, swelling, and discoloration of the leg and, in late stages, as open leg ulcers.

The likelihood of another clot forming is high once you have had aDVT event. The effects of PTS are long lasting and can lessen your quality of life substantially.

Another complication of DVT is a condition known as pulmonary embolism (PE) which occurs when a blood clot breaks loose and travels through the vessel to the lungs. A pulmonary embolism can be fatal if the blood clot significantly blocks blood flow through the lungs. 

What are the symptoms of a DVT?

Nearly 50% of all DVT cases have no noticeablesymptoms. If symptoms are present, they can include leg pain and tenderness, swelling in the calf muscle, ankle, foot, or thigh – usually in one leg only. At times, the skin feels warm and is reddened.


Am I at risk for developing a DVT?

Are you over 60? Are you traveling long distances, thereby sitting for prolonged time withrestricted mobility? Are you overweight and/or lead a sedentary lifestyle? If you answered yes to any of these questions, you may be at risk for developing DVT.

Other risk factors include:

  • Surgery (especially orthopedic) or major injury
  • Smoking
  • Varicose veins
  • High levels of estrogen, such as during pregnancy or when using birth control pills (hormonal contraception)
  • Cancer
  • Prolonged bed rest or immobility, e.g. during hospitalization 

How is DVT diagnosed?

Diagnosis of DVT can be made quickly with a simple ultrasound scan that is painless and risk-free. A specific blood test may be performed to measure the level of “D-dimers” which is a sign of recent clotting. Early diagnosis and treatment greatly reduce your risk of serious complications.

There are other tests that your physician may recommend depending on your medical history. 

How can I prevent a DVT?

DVT is a rare event that, unfortunately, can develop into serious and potentially fatal conditions. Certain risk factors increase the likelihood to develop DVT. These risk factors are cumulative – the more you have, the greater your risk. In addition, the likelihood of another clot forming is high once you have had a DVT event. 

You and your doctor can work together in identifying high risk situations and working out strategies to reduce the risk to develop DVT and/or PE.

Some of the most effective measures for prevention of deep vein thrombosis include 

  • Regular exercise, including stretching and leg movement, when traveling
  • Quit smoking
  • Try to maintain a normal body weight
  • Eat a healthy diet
  • Wear graduated medical compression stockings/socks

Why graduated compression stockings? 

Your doctor may prescribe compression stockings which provide a graduated pressure, with the strongest pressure at the ankle and less pressure at the top of the stocking/sock.

Graduated compression helps to prevent a DVT event and associated complications by improving the blood flow back to the heart. The compression narrows the diameter of the veins, thereby increasing the speed of the blood flow in the veins and reducing the risk of clot formation.

Try Sigvaris products

Sigvaris offers a wide range of ready-to-wear graduated compression stockings/socks, many with natural fiber options. All of our fibers are double wrapped providing you a durable stocking with a comfortable fit.


Deep vein thrombosis (DVT) is classified as an acute venous disorder

Basic medical knowledge on venous disorders

  • With the term Chronic Venous Disorder (CVD) we describe a long-standing condition involving impaired venous return.
  • If vein valves don’t close properly, a reflux results: the blood leaks downwards and stagnates in the vein, thereby leading to venous hypertension. This condition is known as chronic venous insufficiency (CVI) which may cause edema, skin change, and, in some cases, ulcerations.
  • If left untreated, chronic venous insufficiency can result in the formation of serious disorders, including phlebitis and pulmonary embolism. To distinguish the different manifestations of CVD, the CEAP classification system is used.
  • Acute venous disorders usually occur without pre-existing conditions, but they can also be triggered by chronic venous disorders. In any case, medical treatment is immediately required. Acute venous disorders include superficial thrombophlebitis, deep vein thrombosis (DVT), pulmonary embolism, post-thrombotic syndrome, and variceal bleeding.

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Further reading

What is compression therapy?

What is compression therapy?

Medical compression therapy applies a type of elastic device on limbs or other body parts to exert a controlled pressure on them. Thereby, the device squeezes the vein walls together and improves the circulatory rate. Medical compression also helps with reduction of edema and recreates conditions beneficial for the healing of chronic inflammatory disorders.
These factors influence leg health

These factors influence leg health

Many factors can unfavorably influence leg health. These can include lifestyle factors, such as reduced activity, obesity, and/or smoking. Other factors such as advanced age, gender, hormonal changes, and a family history of venous disorders are also influential.
How to get compression products

How to get compression products

What to do when you start having first signs of a venous disease or after you have been diagnosed? Just follow our three steps to get a compression product that best fits your needs. Most of our medical products require either a medical prescription or a professional fitting at a retailer of your choosing. It is recommended that you see your physician who will give you a prescription for the proper compression socks or stocking for you.
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