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Blood Clots

Blood clot definition and facts

  • A blood clot forms to try and repair damage to a blood vessel, either an artery or vein.
  • A blood clot is a gel-like mass formed by platelets and fibrin in the blood to stop bleeding.
  • When blood clots form inappropriately inside an artery or vein, they may cause significant problems because blood flow past the clot is decreased.
  • There are a variety of risk factors and illness that can lead to blood clot formation.
  • Risk factors of blood clots forming in a vein may include:
    • Prolonged immobility
    • Smoking
    • Certain medications, including birth control pills
    • Surgery, especially orthopedic procedures when casts or splints are placed and the patient is immobile
    • Inherited blood clotting disorders.
  • Risk factors of blood clots forming in arteries include:
    • Heart conditions, including atrial fibrillation, a heart rhythm disturbance
    • Smoking
    • High blood pressure
    • High cholesterol
    • Diabetes
    • Trauma or local injury
  • Symptoms of blood clots depend on their location in the body. Some blood clots produce no symptoms until they rupture or become dislodged and travel through the circulatory system to other sites. Symptoms of blood clots in specific body locations are as follows:
    • Symptoms of blood clots in legs (deep vein thrombosis (DVT) are pain, redness, and swelling.
    • Symptoms of an arterial blood clot in a limb (leg or arm) include pain, pale color, and coolness to the touch. and the leg is cool and pale.
    • Symptoms of blood clots in the lung (pulmonary embolus) include chest pain, shortness of breath, and rapid pulse and breathing.
    • Symptoms of a stroke (blood clot in an artery of the brain) include loss of speech, vision, and weakness on one side of the body.
    • Symptoms of a heart attack (blood clot in a coronary artery) are chest pain, shortness of breath, nausea, indigestion, and sweating. Women, people with diabetes, and the elderly may experience other non-specific symptoms.
    • Symptoms of mesenteric ischemia (blood clot to an artery that supplies the intestine) include abdominal pain, nausea, blood in stool.
  • The diagnosis of a blood clot is suggested by the history and physical examination and is often confirmed with an imaging test. Depending upon the location of the blood clot and its cause, treatment may require surgery, anti-coagulation medications, or a combination of the two.
  • Prevention of blood clots involves attention to the risk factors for vascular disease and includes avoiding smoking and lifelong control of high blood pressure, high cholesterol, and diabetes.
  • Serious complications may arise from blood clots, some are life threatening, and individuals should seek urgent or emergent medical care if they believe they may have a blood clot. This is especially true if signs and symptoms of a heart attack or stroke occur.

What are blood clots?

Blood flows through blood vessels (arteries and veins), and is constantly in motion as the heart pumps blood through arteries to the different areas (organs, glands, cells etc.) of the body. Blood is then returned back to the heart by the veins. Blood returns to the heart by the motion of the body. Muscles squeeze blood through the veins back toward the heart. Without motion, blood has a tendency to stagnate by gravity, and stagnant blood then has the tendency to clot.

Blood clotting is an important mechanism to help the body repair injured blood vessels. Blood consists of

  • red blood cells containing hemoglobin that carry oxygen to cells and remove carbon dioxide (the waste product of metabolism),
  • white blood cells that fight infection,
  • platelets that are part of the clotting process of the body, and
  • blood plasma, which contains fluid, chemicals and proteins that are important for bodily functions.

Complex mechanisms exist in the bloodstream to form clots where they are needed. If the lining of the blood vessels becomes damaged, platelets are recruited to the injured area to form an initial plug. These activated platelets release chemicals that start the clotting cascade, using a series of clotting factors produced by the body. Ultimately, fibrin is formed, the protein that crosslinks with itself to form a mesh that makes up the final blood clot.

The medical term for a blood clot is a thrombus (plural=thrombi). When a thrombus is formed as part of a normal repair process of the body, there is little consequence. Unfortunately, there are times when a thrombus (blood clot) will form when it is not needed, and this can have potentially significant consequences.

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Reviewed on 10/28/2016
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