• Thrombosis (Blood Clots) Overview

    When they help prevent bleeding, blot clots are a normal and healthy function of the human body. A thrombosis, however, is an excessive or dangerous blood clot that develops somewhere it shouldn’t. If a blood clot blocks the inside of a blood vessel, serious injury can result. Left untreated, a thrombosis can cause long-term problems, such as permanent damage to internal organs.

    Thrombosis Treatment at Dana-Farber/Boston Children's

    Children and young adults with blood clots are treated at Dana-Farber/Boston Children's Cancer and Blood Disorders Center through our Thrombosis and Anticoagulation Program. Continue reading to learn more about thrombosis or visit the Thrombosis and Anticoagulation Program homepage to learn about our expertise and treatment options for this condition.

    Symptoms & Diagnosis

    Thrombophilia refers to a group of disorders that increases a child’s tendency to develop dangerous blood clots. Inherited thrombophilia is caused by certain genetic conditions. Acquired thrombophilia is caused by lifestyle factors or medical conditions, including immobility, obesity, sedentary lifestyle, trauma, smoking or oral contraceptive use.

    A thrombosis may occur anywhere in a child’s body, but most are in the calf (deep vein thrombosis or DVT) or lungs (pulmonary embolism). Other types of thrombosis include sinus venous thrombosis and arterial thrombosis.

    The symptoms of a blood clot can vary significantly depending on its size and location. Children with a thrombosis in the calf may have the following symptoms:

    • Swelling
    • Pain
    • Redness and warmth
    • Low-grade fever

    In some cases, you may even be able feel the clot in the back of a child’s calf, like a knot under the skin.

    If a child has a pulmonary embolism, he/she may experience:

    • Chest pain
    • Shortness of breath

    Thrombosis is sometimes found accidentally, but mostly because patients develop signs and symptoms of a blood clot. A doctor will conduct a physical examination to evaluate symptoms. The thrombosis will be confirmed through diagnostic imaging tests, including an ultrasound, magnetic resonance imaging (MRI) and computerized tomography (CT or CAT) scan.

    In addition, blood samples may be taken to evaluate if a child’s blood is clotting normally and to identify any abnormalities in the levels of certain proteins. Genetic tests are used to check for hereditary disorders. After all tests are completed, doctors will be able to outline the best treatment options.

    Treatment & Care Options

    Treatment of thrombosis is based on several factors, but is likely to include anticoagulation medications (“blood thinners”), which prevent the clots from growing, decrease the risk of its breaking apart and causing further complications, and help heal the blood vessel. The most commonly prescribed anticoagulation medications are:

    • Oral agents such as warfarin (Coumadin)
    • Intravenous heparin
    • Subcutaneous injections of a low-molecular-weight heparin such as enoxaparin (Lovenox) or dalteparin (Fragmin)
    • Antiplatelet agents such as aspirin, clopidogrel (Plavix) or prasugrel (Effient)

    Other treatments may include wearing compression stockings, remaining active, and applying heat to reduce the swelling and pain caused by the clot.

    Long-term Outlook

    Many DVTs resolve on their own. After a blood clot, however, some people develop long-term pain and swelling in the leg called post-phlebitic syndrome, which is caused by reduced blood flow and damage to the affected vein. Some patients also have changes in skin color, which may not develop for a year or more afterward. Blood clots in the thigh are more likely to break off and travel to the lungs than blood clots in the lower leg or elsewhere in the body. A pulmonary embolism is a life-threatening emergency, requiring immediate medical attention.
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