What is deep vein thrombosis? A deep vein thrombosis (DVT) is a blood clot in a deep vein, oftentimes forming in the lower leg. Important facts to know are: DVTs can develop without warning signs or noticeable symptoms. A blood clot (thrombus) that limits blood flow in the affected area may cause localized pain, swelling, redness and warmth. A DVT that breaks apart from the blood vessel wall is an embolus. The entire thrombus or a fragmented segment may enter the circulation. It can move through the bloodstream to the lungs causing a (PE), which is a life-threatening condition and can cause sudden death. DVTs can be prevented and are readily treated—knowing DVT risk factors and the signs and symptoms of deep vein thrombosis helps reduce the risk of serious consequences. Not all DVTs require treatment right away, but some patients may need medicine or more advanced treatment to remove the clot. Who gets deep vein thrombosis? The exact number of people who develop a DVT every year is not known. A DVT is a type of venous thromboembolism (VTE). A PE is the other type. Some U.S. reports estimate the annual incidence of VTEs is 1 to 2 per 1,000 people, or 300,000 to 600,000 cases a year. However, the actual incidence may be higher because VTE is underdiagnosed. Clinical data on VTE shows: About two-thirds of VTE cases are DVTs, but the proportion of PEs increases with age. The Society of Vascular Surgery estimates about 300,000 people a year in this country develop a first-time DVT. The incidence of VTE increases with age. The rate of VTE is less than 1 per 1,000 people aged 15 years and younger and rises to 5 to 6 per 1,000 people aged 80 years and older. Incidence of VTE in males is slightly greater than in females, except for women’s childbearing years (16 to 44 years), when the rate is higher for women than men. The rate of VTE is higher in White and Black Americans than it is for other ethnicities and races. Approximately 5 to 8% of the U.S. population has at least one genetic risk factor for DVT and PE. What are some conditions related to deep vein thrombosis? A DVT is a vascular condition, which include conditions and diseases affecting any of the blood vessels. Vascular conditions related to DVT include: Chronic venous insufficiency—malfunctioning valves in the veins, typically in the legs, that causes blood to pool Pulmonary embolism—sudden blockage in a lung artery, most always caused by a DVT Thrombophilia—an acquired or genetic susceptibility for higher-than-normal blood clotting Varicose veins—malfunctioning valves in the superficial veins of the legs that causes blood to pool and the veins to bulge How does deep vein thrombosis affect quality of life? DVT treatment is most effective when the blood clot is caught early. After the clot is dissolved or removed, swelling and pain subside and go away completely. However, people who need long-term anticoagulant therapy are at increased risk for bleeding. They may require regular blood testing to maintain a safe and effective anticoagulant dose, depending on the drug. After a first-time DVT, people have an increased risk of a second DVT—about 30% of patients have a second event within 10 years, even with standard anticoagulant therapy. Overall, quality of life can be impaired for up to four months or longer after a first-time DVT. One-third to one-half of people with a DVT develop post-thrombotic syndrome. It is more likely to develop in patients who had a DVT that damaged the walls or valves of the vein. This allows blood to pool in the vein causing such symptoms as long-term swelling of the area, pain, skin discoloration, skin ulcers, and itchiness. Post-thrombotic syndrome can develop weeks, months or even years after the DVT. It can cause chronic problems and significant disability. DVTs and complications put a financial burden on the patient and healthcare system overall. Annual costs for both DVT and PE are estimated at approximately $8,000 to $16,000 per patient based on medical claims data. Can you die from deep vein thrombosis? The most serious threat from DVT is PE. When an embolus lodges in the lung, it blocks blood flow and prevents freshly oxygenated blood from reaching other parts of the body, including the brain. More than 50,000 people die from PE every year in the United States. Reviews on the epidemiology of DVT and PE estimate that 6% of DVT cases and 10% of PE cases are fatal within one month of the episode. The actual rate of PE deaths may be as high as 30%. What causes deep vein thrombosis? Clot formation—coagulation—is a normal, protective process in response to injury and bleeding. Blood clotting requires many different blood clotting (coagulation) factors to form a clot. There are also anticoagulation factors. Abnormal amounts of these factors or conditions that affect their function can lead to either excessive clotting or excessive bleeding. Several conditions can increase the risk of DVT: Slow blood flow, which can be caused by little-to-no body movement. Paralysis, hospitalization, and bed confinement due to surgery, injury or illness can slow blood flow. Slower blood flow can inhibit the normal action of anticoagulation factors to favor clotting. Injury to the vein Catheter placement in a central vein (central line, or central venous catheter) Increased estrogen from pregnancy, hormone-based birth control, or hormone replacement therapy. Estrogen increases the levels of clotting factors. Annually, about 1 in 3,000 women taking birth control pills develop a blood clot. Chronic illnesses including heart and lung disease and cancer, which can cause blood to clot easier Inherited clotting disorders, such as thrombophilia Obesity A personal or family history of DVT, as well as increasing age, increases the risk of DVT. How is deep vein thrombosis diagnosed? Tests to diagnose a DVT include: Duplex ultrasound, the most common method of diagnosing a DVT. A duplex ultrasound combines regular ultrasound with Doppler technology to track moving objects, such as blood flowing through blood vessels. MRI (magnetic resonance imaging) uses a magnet-based technology to create detailed pictures of blood vessels including the pulmonary arteries. CT (computed tomography) takes multiple X-ray images of the body from different angles to produce a highly detailed image. A CT scan with contrast agent administered into a vein is CT angiography. The contrast highlights the circulatory system. D-dimer blood test measures fibrin proteins that a blood clot releases when it dissolves. Higher-than-normal levels of fibrin suggest DVT. In case of a positive D-dimer test and signs and symptoms of DVT or PE, the doctor is likely to order CT angiography to confirm the diagnosis. Additional diagnostic tests may help determine the underlying cause of DVT. What are common treatments for deep vein thrombosis? Doctors monitor some DVTs for signs the clot is growing larger instead of treating it immediately. It is also possible for a DVT to dissolve on its own. When DVT treatment is necessary, common approaches include: Anticoagulants, or blood thinners. These medicines keep the clot from growing larger and prevent more clots from forming. If the patient has an ongoing risk of blood clots, the patient may need to take blood thinners long-term. Thrombolytics, or clot-busting drugs. These medicines quickly dissolve the clot. This treatment, administered directly to the clot via a catheter, is best in emergency situations when there is a high risk the clot will lead to a PE. Other methods include: Thrombectomy, a minimally invasive or open surgical procedure to remove the clot with or without clot-busting medicine Vena cava filter, a medical procedure for patients at risk of blood clots but who do not respond to or cannot tolerate blood thinners. A surgeon places the filter in the large vein (vena cava) before it returns blood to the heart. The filter retains clots and other emboli before they have a chance to enter the heart and lungs. Compression stockings, which the patient wears to improve circulation in the legs and prevent additional clots from forming Additional deep vein thrombosis facts Organizations around the world are working to raise awareness of DVT and PE, particularly prevention in the hospital setting. The National Institutes of Health funds research to advance DVT awareness, prevention, diagnosis and treatment. In 2007, the National Blood Clot Alliance and the Centers for Disease Control and Prevention began the Stop the Clot awareness program. March is DVT awareness month.