Deep vein thrombosis

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at April 19, 2016
Start › Diseases › Deep vein thrombosis

A deep vein thrombosis (DVT) is a blood clot that forms in a vein, usually in the leg. The complications associated with a deep vein thrombosis can be severe, as it is linked closely with the occurrence of pulmonary embolism, a life-threatening condition.

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Definition & Facts

A thrombus or blood clot happens when platelets and fibrins stick together and form a solid clump. Thrombosis occurs when that clot forms and stays in the blood vessels, preventing blood from flowing. The arms, lower legs, upper thighs, and pelvis are all places where deep vein thromboses are likely to occur. When a clot gets too big, it can block blood vessels, or it may break off and travel to other parts of the body, at which point it becomes an embolism.

Symptoms & Complaints

The primary symptom of a deep vein thrombosis is leg swelling or arm swelling. The skin of the affected area may become very warm, red, or discolored, and veins can become swollen or distended. While trying to use the affected limb, a person with DVT might notice that it feels weak or painful to move or put weight on it.

If a vein is completely blocked, resulting in an acute deep vein thrombosis, the whole limb will become bluish, swollen, and very painful, and this is far more noticeable than a non-obstructive deep vein thrombosis.

The primary danger associated with a deep vein thrombosis is that it can leave its original point and travel through blood vessels until it reaches the lungs. If a deep vein thrombosis reaches the lungs, this is called a pulmonary embolism, and it can cause lung collapse or heart failure.

Causes

There are three primary causes of deep vein thrombosis, and these three causes are often referred to as Virchow's Triad. The first cause is stasis, which occurs when normal blood flow is interrupted and becomes slower, which is often the result of a person remaining immobile for a long period of time. Injuries to the walls of blood vessels from physical damage or infections is also another cause of deep vein thrombosis because it causes an increase in clots. The other cause of deep vein thrombosis is hypercoagulant blood, which happens when a person has a condition that makes blood clot together quickly.

The main risk factors of deep vein thrombosis include obesity, blood clotting disorders, pregnancy, smoking, disabilities that limit movement, and birth control pills. People with chronic health conditions, like cancer or heart disease, are also more likely to develop a deep vein thrombosis.

Diagnosis & Tests

Most doctors will start the diagnostic process by examining the patient's medical history and ruling out other conditions first. Blood clots are usually diagnosed with an imaging test or a blood test. Imaging tests can carry some risks of radiation, so the first test that a doctor will do for a non-acute case is often a blood test. People with a deep vein thrombosis have higher levels of D-dimer, a blood component related to clot degeneration.

Serious cases are often diagnosed immediately through an imaging test. An ultrasound, CT scan, or MRI can be used to create an image of the veins, and the blood clot will be apparent with these imaging tests. Often, smaller deep vein thromboses are diagnosed before they become symptomatic because the blood clot is revealed while they are being tested for an unrelated issue. An X-ray test can also be used to perform a venography, which reveals a blood clot after a dye is injected into the large veins of the feet.

Treatment & Therapy

Treatment for a deep vein thrombosis will depend on the severity of the cases. In cases where the blood clot is very small, doctors will often recommend that a patient take anticoagulants, which are also called blood thinners. Blood thinners like heparin, warfarin, and dabigatran keep clots from growing in size or breaking off and traveling to more dangerous locations in the body; while they prevent the situation from worsening, the body naturally dissolves the clot.

If the blood clot is large and poses an immediate threat, the doctor may recommend a catheter-directed thrombolysis. In this procedure, a catheter is inserted into the vein and a thrombolytic drug that breaks up the clot is injected directly into the clot. However, this treatment can cause side effects such as a stroke. If neither of the above options work, the doctor may try a surgery to remove the clot. A venous thrombectomy can be done to directly cut the clot out of the vein.

Prevention & Prophylaxis

Deep vein thromboses are often preventable. Regular exercise and healthy diet improve blood flow, lower blood pressure, and reduce weight, so these lifestyle choices are some of the best ways to prevent a clot. Blood flow can also be encouraged by wearing compression stockings that keep blood from pooling in the feet and calves.

If it is necessary to sit for a long time while traveling or working, clots can be avoided by regularly getting up to move around. For patients who are particularly at risk for developing clots, doctors may prescribe that they take blood thinning medication.

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