Venous Thoracic Outlet Syndrome

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    Venous Thoracic Outlet Syndrome

    Venous Thoracic Outlet Syndrome

    The shoulder area, showing the top ribs, the clavicle, and the subclavian vein.

    Venous thoracic outlet syndrome (TOS) is a condition that happens when the subclavian vein is squeezed or compressed. The subclavian vein is the vein that returns blood from the arm and hand to the heart. To reach the arm, this vein must pass through the thoracic outlet. This is a tight space under the collarbone (clavicle) and above the top rib.

    Depending on which structures are affected, you may have symptoms on one or both sides of your body.

    What are the causes?

    This condition may be caused by anything that could narrow your thoracic outlet, such as having a cervical rib. This is an extra rib at the base of your neck. TOS can sometimes be caused by a blood clot in the subclavian vein.

    What increases the risk?

    The following factors may make you more likely to develop this condition:
    • Doing work with your arms that involves repeated movements and takes a lot of effort.
    • Being male.
    • Being overweight.
    • Poor posture.
    • Having an indwelling catheter in your upper arm to deliver certain kinds of medicines.
    • A history of Ehlers–Danlos syndrome.

    What are the signs or symptoms?

    Symptoms of this condition include:
    • Pain and swelling of your whole arm.
    • A feeling of heaviness or tightness in your arm.
    • Your arm or hand turning a blue color (cyanosis).

    These symptoms may be worse when you hold your arms over your head.

    How is this diagnosed?

    This condition may be diagnosed based on:
    • Your symptoms and a physical exam. You may be asked to hold your arms over your head and in other positions to see if your symptoms get worse.
    • Tests to confirm the diagnosis and to find out the cause of your TOS. These tests may include:
      • X-rays to look for a problem in the ribs, such as a cervical rib.
      • An ultrasound. This test uses sound waves to create an image.
      • A CT scan.
      • An MRI scan.
      • An angiogram or venogram. In these tests, X-rays are done after a dye is injected into an artery or vein.
      • A pulse volume recording. This test measures the pulses in your wrists.

    How is this treated?

    This condition may be treated with:
    • Medicine, including blood thinners or blood clot dissolvers.
    • A procedure to open up the clotted vein and restore blood flow (angioplasty).
    • Surgery to remove a blood clot (thrombus).
    • Surgery to remove the cervical rib to make more space in the thoracic outlet.

    Follow these instructions at home:


    • If you are taking blood thinners:
      • Talk with your health care provider before taking aspirin or NSAIDs. These medicines can raise your risk of bleeding.
      • Take your medicines as told. Take them at the same time each day.
      • Do not do things that could hurt or bruise you. Be careful to avoid falls.
      • Wear an alert bracelet or carry a card that says you take blood thinners.
    • Take over-the-counter and prescription medicines only as told by your provider.


    • Do exercises as told by your provider or physical therapist.
    • Do not lift anything that is heavier than 10 lb (4.5 kg) until your provider says that it is safe.
    • Do not carry heavy bags over your shoulder or do repeated lifting of heavy objects over your head.
    • Take breaks often if you work at a keyboard or do other work that involves repeated movements of your hands and arms. Stretch and rest your arms during these breaks.

    General instructions

    • Stay at a healthy weight. Lose weight as told by your provider.
    • Maintain good posture.
    • Keep all follow-up visits. Your provider will check to see if your symptoms are improving with treatment.

    Contact a health care provider if:

    • You have pain, cramps, numbness, or tingling in your arm or hand.
    • Your arm or hand often feels tired.
    • Your arm turns a darker and different skin color than usual.
    • Your hand feels cold.
    • You have frequent headaches or neck pain.
    • You have muscle loss in your hand.

    Get help right away if:

    • You lose feeling in your arm or hand.
    • You cannot move your fingers.
    • Your fingers turn a dark color.

    This information is not intended to replace advice given to you by your health care provider. Make sure you discuss any questions you have with your health care provider.

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