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How does Deep Vein Thrombosis develop?

Deep Vein Thrombosis

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Deep vein thrombosis, often abbreviated as DVT, is a medical condition that occurs when a vein deep inside the body becomes partially or fully obstructed by a blood clot. Deep vein thrombosis typically affects the veins located within a patient’s legs or pelvic area. Blood clots in the arms and upper body are much less common.

A variety of factors can lead to increased risk of DVT. Risk increases with age. There are also genetic factors that may be inherited. Certain medical conditions, like cancer, obesity, inflammatory bowel disease, collagen vascular disease, heart failure, and surgery increase the risk of forming a blood clot. Other factors such as smoking, bedrest, restricted mobility, injuries or long-distance travel also increase the risk. Finally, women who are pregnant or who are taking birth control pills or hormone replacements also have an increased risk of developing deep vein thrombosis.

Although patients diagnosed with DVT may complain of pain from the affected vein, about 50% of patients are without symptoms. In many cases, the area affected by a deep thrombus may appear red and swollen. The skin covering that area of the body can also feel warm to the touch as a result of the inflamed or engorged veins. The most common diagnostic test for deep vein thrombosis is ultrasound, which can be used to visualize the veins and look for signs of a blood clot. The ultrasound test may need to be repeated over several days. Your physician may also order a D-dimer test to help rule out DVT.

The most dangerous thing that can happen in a patient with deep vein thrombosis is the formation of a pulmonary embolism, or PE. Pulmonary embolism occurs when a blood clot breaks off from the deep vein and travels to the lungs. The patient needs emergency medical attention if this occurs as the condition may be life-threatening. Pulmonary embolism symptoms include heart palpitations, breathing problems, and pain in the chest when the patient inhales, among others.

The goal of DVT treatment is to prevent the blood clot from expanding, reducing the risk of post-thrombotic syndrome, preventing the blood clot from breaking loose and traveling to your lungs, and reducing the chances of recurrence of DVT. Common treatments for deep vein thrombosis include compression stockings and blood thinners. Thrombolysis and/or blood clot removal may be used in some cases of severe DVT of certain veins. A filter may be recommended to reduce the chance of pulmonary embolism, primarily if you are not a candidate for blood thinners.

DVT can also cause post-thrombotic syndrome, a condition where blood pools in the legs. Post-thrombotic syndrome may lead to chronic swelling, aching, skin problems such as discoloration and inflammation and venous ulceration.

If you think you may be experiencing symptoms suggestive of deep vein thrombosis, contact a vein specialist. If you develop signs or symptoms of a pulmonary embolism, such as chest pain, lightheadedness and difficulty breathing, seek medical care immediately.


Reviewed by Steven E. Zimmet, MD, RVT, FACPh
Editor of Phlebology
President, Zimmet Vein & Dermatology
Past-President, American College of Phlebology

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