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Blood clotting is a normal process that occurs in the body to prevent bleeding. The body makes blood clots and then breaks them down. Under certain circumstances, the body may be unable to break down a clot, which may result in a serious health condition.
Abnormal blood clotting in the veins is related to a combination of several problems such as "sluggish" blood flow through the veins, an over-increase in clot forming factors, and/or an injury to the blood vessel wall.
Blood clots can form in arteries and/or veins. Clots formed in veins are called venous clots. Veins of the legs can be classified as superficial veins (close to the surface of the skin) or deep veins (located near the bone and surrounded by muscle).
Deep vein thrombosis (DVT) a major cause
Left untreated, a deep vein thrombosis (DVT) can break off and travel in the circulation, getting trapped in the lung, where it blocks the oxygen supply, causing heart failure. This is known as a pulmonary embolism, which can be fatal.
With early treatment, people with DVT can reduce their chances of developing a life threatening pulmonary embolism to less than one percent. Blood thinners are effective in preventing further clotting and can prevent a pulmonary embolism (PE) from occurring.
Venous clots most often occur in the deep veins of the legs. This condition is called deep vein thrombosis, or deep vein clot. Once a clot has formed in the deep veins of the leg, there is a potential for part of the clot to break off and travel (embolize) through the bloodstream to another area of the body. Deep vein thrombosis is the most common cause of a pulmonary embolism. Therefore, the term venous thromboembolism (VTE) may refer to deep vein thrombosis and/or the complication, pulmonary embolism.
Other less frequent sources of pulmonary embolism are a fat embolus, amniotic fluid embolus, air bubbles, and a deep vein thrombosis in the upper body. Clots may also form on the end of an indwelling intravenous (IV) catheter, break off, and travel to the lungs.
What are the risk factors for pulmonary embolism?
Risk factors that are associated with the processes that may increase the risk of a venous thromboembolism include:
Genetic conditions that increase the risk of blood clot formation
Surgery or trauma (especially to the legs)
Situations in which mobility is limited, such as extended bed rest, flying or riding long distances, or paralysis
Previous history of clots
Cancer and cancer therapy
Certain medical conditions, such as heart failure, chronic obstructive pulmonary disease (COPD), hypertension (high blood pressure), stroke, deep vein thrombosis (DVT), and inflammatory bowel disease (chronic inflammation of the digestive tract)
Certain medications, such as oral contraceptives (birth control pills) and hormone replacement therapy (estrogen pills for post-menopausal women)
Pregnancy (during and after pregnancy, including cesarean section)
Varicose veins (enlarged veins in the legs)
A risk factor is anything that may increase a person's chance of developing a disease. It may be an activity, such as smoking, diet, family history, or many other things. Different diseases have different risk factors.
Although these risk factors increase a person's risk, they do not necessarily cause the disease. Some people with one or more risk factors never develop the disease, while others develop disease and have no known risk factors. Knowing your risk factors to any disease can help to guide you into the appropriate actions, including changing behaviors and being clinically monitored for the disease.
Clinical trials are research studies that evaluate a new medical approach, device, drug, or other treatment. As a Stanford Health Care patient, you may have access to the latest, advanced clinical trials.
Open trials refer to studies currently accepting participants. Closed trials are not currently enrolling, but may open in the future.