What Is Deep Vein Thrombosis?

Deep vein thrombosis refers to a blood clot that develops inside a larger vein - usually deep within the lower leg or thigh. DVT strikes about half a million Americans every year and causes up to 100,000 deaths. The danger is that part of the clot can break off and travel through the bloodstream, where it can lodge in the lungs causing a blockage in blood flow, organ damage, and death.

Symptoms of Deep Vein Thrombosis

Unfortunately, DVT often goes unnoticed. About half of people with DVT have no warning signs. Symptoms may include:

Redness

Swelling

Tenderness or pain

These happen in the area of the blood clot, which is usually the leg (notice the swelling in the leg below the right knee seen here).

Dangers of DVT: Pulmonary Embolism

If part of the clot breaks loose and travels through the bloodstream, the results can be life-threatening. A clot that blocks the blood supply to the lungs is called a pulmonary embolism. Symptoms include trouble breathing, low blood pressure, fainting, faster heart rate, chest pain, and coughing up blood. If you have any of these symptoms, call 911 or go to the emergency room.

What Causes DVT?

Anything that damages the inner lining of a vein may cause DVT, including surgery, injury, or an immune system response. Blood that is thick or flows too slowly is more likely to form a clot, especially in a vein that is already damaged. Other things that raise the risk for blood clotting include genetic disorders, hormone changes, and sitting for long periods of time (such as when flying).

Who’s at Risk for DVT?

People with a higher risk of DVT include:

People who have cancer

People who have had surgery

Anyone on extended bed rest

The elderly

Smokers

Long-distance travelers

People who are overweight or obese

More risk factors are discussed in the next slides.

DVT and Pregnancy

Women have a greater risk of developing DVT during pregnancy and the four to six weeks after giving birth. This is due to higher levels of estrogen, which may make blood easier to clot. The pressure of an expanding uterus can also slow blood flow of the veins as well. Certain blood disorders can boost the risk even more.

DVT and Hormonal Birth Control

Like pregnancy, hormonal birth control and postmenopausal hormone therapy change blood chemistry and may increase risk of DVT, even in women who don't have blood disorders.

DVT and Travel

Traveling to new and faraway places can be exciting. Squishing into a coach seat for a long international flight is not. Studies show long-distance travel lasting more than four hours doubles your risk of developing DVT. This includes travel by air, bus, train, or car. Not moving around in these cramped conditions can cause sluggish blood flow. 

Diagnosing DVT

An ultrasound is most often used to diagnose DVT. It uses sound waves to create a picture of blood flow in the affected area and can reveal a clot. Before recommending an ultrasound, your health care provider will examine you and check you for signs of DVT. You may be asked about your medical history, medications you are taking, family history, and about any other factors that could raise your risk of DVT.

Treating DVT: Anticoagulants

Anticoagulants, which make the blood thinner, are the most common DVT treatment. They are taken as a pill or by injection. They can’t break up an existing clot, but they prevent new blood clots from forming, giving the body time to dissolve the clot on its own.

Treating DVT: Clot Busters

Medications that actually dissolve blood clots are called thrombolytics. They can cause sudden, severe bleeding, so they are used only in emergencies: for example, to dissolve a life-threatening blood clot that's traveled to the lungs and is causing severe symptoms. Thrombolytics are given by IV in a hospital.

Side Effects of DVT Medications

Because anticoagulants thin the blood, people who take them may get bruises often or bleed more easily. Internal bleeding can be life-threatening, so if you take an anticoagulant, your doctor can test your blood to make sure it's not too thin. Some newer medications do not require routine laboratory monitoring of their blood-thinning effect. 

Warning Signs of Internal Bleeding

Signs of internal bleeding in the belly include pain, vomit that is red or looks like coffee grounds, and bright red or black stools. Bleeding in the brain can cause severe headache or symptoms of stroke such as vision changes, abnormal movement, and confusion. Call 911 or go to the emergency room if you develop any of these symptoms. Also check with your health care provider if you bleed a lot from minor injuries.

Treating DVT: Vena Cava Filter

If you can't take anticoagulants or they are not working, your doctor may recommend inserting a filter into a large vein called the vena cava. This filter catches breakaway clots and prevents them from traveling to the lungs. The filter won't stop new clots from forming or cure DVT itself, but it can prevent a life-threatening pulmonary embolism.

Treating DVT: Compression Stockings

Compression stockings apply pressure to keep the blood in the legs from pooling and clotting. They reduce swelling and help relieve discomfort in a leg where a clot has already formed. You can get compression stockings over the counter or by prescription. Prescription stockings provide greater pressure.

Treating DVT: Home Care

To reduce swelling and discomfort, keep the affected leg raised when possible. If your doctor has recommended compression stockings, be sure to wear them even when you're at home.

Long-Term Complications of DVT

Once a blood clot is gone, DVT sometimes leaves behind an unpleasant calling card. You may have long-term swelling, changes in skin color, and pain where the clot was. These symptoms, known as post-thrombotic syndrome, sometimes show up even a year after the clot.

Preventing DVT: Exercise

Being active increases your blood flow, keeping it from pooling and clotting. Exercising the lower leg muscles in particular can help prevent DVT. When you're not active -- at your desk, for example -- take breaks to stretch your legs. Get up and walk around if you can. Frequent exercise also reduces the risk of obesity, which contributes to DVT risk.

Preventing DVT: Travel Tips

When traveling for more than four hours, avoid tight clothing and drink plenty of water. Get up and walk around at least every two to three hours. If you have to stay in your seat, find ways to keep your legs active. Try clenching and releasing your leg muscles or lifting and lowering your heels with your toes on the floor. And be sure to do plenty of sightseeing by foot once you arrive.