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Deep Vein Thrombosis

What is deep vein thrombosis?

You have three kinds of veins. Superficial veins lie close to the skin, and deep veins lie in groups of muscles. Perforating veins connect the superficial veins to the deep veins with one-way valves. Deep veins lead to the vena cava, your body's largest vein, which runs directly to your heart. Deep vein thrombosis (DVT) is a blood clot in one of the deep veins. Usually, DVT occurs in your pelvis, thigh, or calf, but can also occur less commonly in your arm, chest, or other locations. DVT can cause sudden swelling, pain or a sensation of warmth. DVT can be dangerous because it can cause a complication known as pulmonary embolism. In this condition, a blood clot breaks free from your deep veins and lodges in your lungs. This clot can block blood flow in your lungs, which can strain your heart and lungs. A pulmonary embolism is a medical emergency. A large embolism can be fatal in a short time.

What are the symptoms?

About half of all DVT cases do not cause symptoms. The symptoms you feel can depend on the location and size of your blood clot. They include swelling, tenderness, leg pain that may worsen when you walk or stand, a sensation of warmth, and skin that turns blue or red.

What causes DVT?

When something goes wrong with your body's blood clotting system, DVT can occur. Often, poor blood flow, or stagnation of blood flow, in your leg veins increases the risk for DVT. This poor flow can occur when you are not able to move for long periods of time. As a result, when your blood pools in your veins, clots are more likely to form.

Some specific causes of DVT include:

What tests will I need?

DVT TransducerYour physician will ask questions about your general health, medical history, and symptoms. In addition, your physician will conduct a physical exam. To confirm a diagnosis of DVT, the physician may order a duplex ultrasound test or a venogram. Duplex ultrasound uses high-frequency waves higher than human hearing can detect. Duplex ultrasound allows your physician to measure the speed of blood flow and to see the structure of your veins and sometimes the clots themselves. A venogram is an x ray that allows your physician to see the anatomy of your veins and sometimes the clots within them. During this test, your physician injects a dye that makes your veins appear on an x ray.

How is DVT treated?

Your physician or vascular surgeon can usually treat DVT with medications or minimally invasive procedures. Rarely, surgery may be required.

If you have DVT, your physician may use an anticoagulant drug, or blood thinner, called heparin. They don't truly thin your blood, but they help keep your blood from clotting too easily. Heparin helps new clots from forming and keeps clots you already have from growing larger. Heparin cannot break up a clot you already have. Heparin acts rapidly but must be given by vein. Alternatively, your physician may prescribe a medication known as a low molecular weight heparin (LMWH). This has many of the same effects as heparin, but is given through an injection in the abdomen once or twice a day.

Usually, you will receive heparin (or LMWH) for several days. After that, you will take an anticoagulant pill called warfarin. It can take a few days for the warfarin to work, and during that time you may be on both heparin (or LMWH) and warfarin. While you are receiving medication, your physician will order blood tests to make sure your anticoagulation level is adequate to prevent clots, but not high enough to cause bleeding.

If your physician wants to dissolve the clot, he or she may recommend thrombolysis. In this procedure, your vascular surgeon injects clot-dissolving drugs through a catheter directly into the clot. Thrombolysis has a higher risk for bleeding complications and stroke than anticoagulant therapy. However, thrombolysis can also dissolve very large clots. Your vascular surgeon may prefer to use thrombolysis.

Rarely, physicians recommend surgery to remove a deep vein clot. The procedure is called venous thrombectomy. You may need this surgery if you have a severe form of DVT called phlegmasia cerulea dolens, which does not respond to adequate non-surgical treatment. Phlegmasia cerulea dolens, if not adequately treated, can cause gangrene, which is tissue death. Gangrene is very serious and can lead to amputation.

A metal filter can protect you from a pulmonary embolism if you are unable to take anticoagulants. This device is called a vena cava filter. The vena cava is the large vein in your abdomen that carries blood to your heart and lungs. Your physician may recommend a vena cava filter if you are not a candidate for anticoagulation. Vena cava filters trap the clots that break away from your leg veins before they can reach your lungs.

What can I do to stay healthy?

Sleeve fitted during surgery to compress the legsPhysicians know that DVT is more likely if you have surgery. If you are scheduled for surgery, your physician may recommend one or more of the following, to prevent DVT:

Images reproduced by kind permission Vascular Web