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What Is Deep Vein Thrombosis?
Deep vein thrombosis (DVT) is a blood clot that develops in the deep and larger veins in one or both legs, usually in the lower leg (figure shows DVT in the left thigh). DVTs can be dangerous because the clot may become large, break apart, and go through the blood vessels and lodge in the lungs, resulting in decreased or no blood flow to the lungs. This situation may lead to rapid organ damage and even death. About 100,000 to 300,000 deaths per year are estimated to be due to DVTs.
Deep Vein Thrombosis Symptoms
Many DVTs are not detected by patients or their doctors; about half have no warning signs. Symptoms, when present, may include one or more of the following:
- Edema in the affected leg (most specific symptom), with possible skin blanching
- Leg tenderness, sometimes with a palpable bump or mass
- Leg pain
- Leg warmth and/or leg skin redness over the DVT
- Lung symptoms of pulmonary edema (PE), a complication of a DVT
- A positive Homan’s sign (calf pain when foot is flexed upwards)
DVT Dangers: Pulmonary Embolism
The major complication of a DVT is a pulmonary embolism (PE). When a DVT breaks away from its formation site, it can reach the lung vessels and block blood flow. This can be a life-threating emergency. Symptoms of a PE include shortness of breath, chest pains, a fast heart rate, low blood pressure, and loss of consciousness or fainting. Some people may cough up blood. A PE is a medical emergency. Call 9-1-1 if a person has symptoms of a PE.
What Are the Causes of DVT?
There are many things that can contribute to causing a DVT. For example, venous damage, increased blood viscosity, surgery, infectious diseases, age 75 and older, cancer, genetic disorders, hormonal changes, certain drugs, previous DVT, and even the lack of leg movement or sitting in a way that decreases leg blood circulation may contribute to DVT (or PE) formation.
Who Is at Risk for DVT?
Risk factors are similar to those causes listed in the previous slide and include:
- Previous DVT (or PE)
- Age 75 or older
- Immobilization (3 or more days)
- Long car or plane trips (especially if sitting is constant without breaks for walking)
- Any major medical or surgical problems (for example, cancer, stroke, heart attack, congestive heart failure, burns, spinal cord injuries, multiple trauma, leg fractures, and many others)
- IV drug abuse
- Certain drugs (oral contraceptives, estrogens, heparin-induced thrombocytopenia)
- Genetic causes
DVT and Pregnancy
Due to high levels of estrogen in pregnancy, during and until about 4 to 6 weeks after delivery, women have a higher risk for DVTs. Estrogen may promote clotting and the large uterus can press against vessels and slow blood flow. Such women (and some men) that have other health problems such as genetic clotting disorders, lupus, homocystinuria, and other blood disorders are also at higher risk for DVT development.
DVT and Hormonal Birth Control
Hormonal birth control and postmenopausal hormonal therapy may increase an otherwise normal woman’s risk of DVTs.
DVT and Travel
As mentioned, traveling can be a significant risk factor for DVTs. Sitting with bent knees on an airplane or in a bus, car, or train markedly increases a person’s risk of developing a DVT. This risk increase is due to sluggish blood flow in the bent and stationary legs. Just a few hours (about 4 or so) is enough to increase DVT risk.
After doing a person’s history and physical exam, if the doctor suspects a DVT, ultrasound or ultrasonography is usually the first test of choice to detect the clot. This test has high sensitivity and specificity for DVTs and is not invasive. Other tests are available, but most are invasive while ultrasound is not.
Treating DVT: Anticoagulants
Anticoagulants, such as heparin, low-molecular-weight heparin, or Coumadin, have been the main treatments for DVTs. On occasion, mechanical thrombolysis has been used. IV thrombolytics are no longer recommended for DVTs because of the increased chance for bleeding.
Treating DVT: Clot Busters
Although IV thrombolytics (that dissolve blood clots but may cause excessive bleeding in some people) are not recommended for DVT treatment, they are sometimes used for treating life-threatening DVT complications such as a PE. IV thrombolytics are mainly used in a hospital setting only. The benefits of IV thrombolytics when treating an emergency PE outweigh the risks of bleeding, in most patients.
Side Effects of DVT Medications
Even anticoagulants can cause excessive bleeding, although usually not as much as IV thrombolytics. People can develop easy bruising and other signs of bleeding. Consequently, people taking anticoagulants need to be checked occasionally by their doctor to make sure the blood is not too thin (over anticoagulated) or too thick (not properly anticoagulated).
Warning Signs of Internal Bleeding
If a person takes too much anticoagulation medicine (over anticoagulated) or even with IV thrombolytics, internal bleeding can occur. Signs and symptoms of internal bleeding include abdominal pain, bloody or blood-tinged vomit, severe headaches, or stroke symptoms (due to bleeding into the brain). Similar symptoms can occur in patients that undergo trauma like a fall or a car wreck due to thinned blood. If you or someone you are with experiences any of the above symptoms, call 9-1-1 immediately.
Treating DVT: Vena Cava Filter
For those patients who have had multiple DVTs and/or PEs and especially those who cannot take anticoagulants for whatever reasons, the doctor may recommend surgically placing a device that permanently sits in the vena cava that is designed to trap clots before they can reach the lungs. The devices are vena cava filters (see picture) that prevent most clots, formed from DVTs, from reaching the lung vessels -- thus preventing PEs. Although the filters do not prevent or cure DVTs, they are good at preventing future PEs although some devices may be better than others.
Treating DVT: Compression Stockings
Treating and preventing DVTs can be done with several methods. One common method is for people to use compression stockings. These stockings function by applying external pressure to the legs that reduces swelling and assists the leg (calf) muscles to pump blood. This added pumping action helps the patient avoid developing DVTs. They may also reduce the pain and swelling in a person who has developed a DVT.
Treating DVT: Home Care
Wearing compression stockings is useful not only in the hospital setting but also at home, especially if your doctor recommends them. In addition, if you have the opportunity to raise your legs up (a height equal to or above your heart level while reclined), this is a good way to reduce leg edema and aid blood circulation in the legs.
Long-Term Complications of DVT
A complication that may occur with DVTs is termed post-thrombotic syndrome (PTS). PTS is long-term swelling and pain, usually accompanied by skin color changes that persist at the DVT site even if the DVT is gone. PTS may occur sometimes much later (up to 2 years) after the DVT has gone.
DVT Prevention: Exercise
DVT prevention methods center on the process of keeping good blood flow to your legs. Being active and avoiding long (about 2 to 3 hour) stretches of time at a desk or sitting immobile with legs bent is an excellent way to reduce the chance of developing a DVT. So take a break, get up, and stretch your legs and get them moving often during the day.
DVT Prevention: Travel Tips
There are some situations where you may have to be in a seated position for long periods of time (the dreaded overseas flight with stormy weather). Be prepared! Wear loose clothing and drink water to stay hydrated; these two methods will permit better blood circulation and less blood viscosity, respectively. Also, keep your legs active even while seated by stretching, flexing your calf muscles, lifting your legs and thighs up and down, and wiggling all your toes. If you are permitted to get out of your seat for a short time, try to do so every 2 hours. After you arrive, exercise! These methods should help people avoid getting a DVT.
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