• A slowdown of blood flow.

• Damage to a vein.

• A condition that causes blood to clot more easily, such as certain bleeding disorders.

• Obesity.

• Being older, especially older than age 60.

• Being inactive or not moving around (sedentary lifestyle). This may include:

  • Sitting or lying down for longer than 4–6 hours other than to sleep at night.

  • Being in the hospital, or having major or lengthy surgery.

  • Having any recent bone injuries, such as breaks (fractures), that reduce movement, especially in the lower extremities.

  • Having recent orthopedic surgery on the lower extremities.

• Being pregnant, giving birth, or having recently given birth.

• Taking medicines that contain oestrogen, such as contraceptive or hormone replacement therapy.

• Using products that contain nicotine or tobacco, especially if you use a hormonal contraceptive.

• Having a history of a blood vessel disease (peripheral vascular disease) or congestive heart disease.

• Having a history of cancer, especially if being treated with chemotherapy.

• Swelling, pain, pressure, or tenderness in an arm or a leg.

• An arm or a leg becoming warm, red, or discoloured.

• A leg turning very pale or blue. You may have a large DVT. This is rare.

• Your medical history and a physical examination.

• Tests, such as:

  • Blood tests to check how well your blood clots.

  • Doppler ultrasound. This is the best way to find a DVT.

  • CT venogram. Contrast dye is injected into a vein, and X-rays are taken to check for clots. This is helpful for veins in the chest or pelvis.

• The cause of your DVT.

• The size and location of your DVT, or having more than one DVT.

• Your risk for bleeding or developing more clots.

• Other medical conditions you may have.

• Taking a blood thinner medicine (anticoagulant) to prevent more clots from forming or current clots from growing.

• Wearing compression stockings.

• Injecting medicines into the affected vein to break up the clot (catheter-directed thrombolysis).

• Surgical procedures, when DVT is severe or hard to treat. These may be done to:

  • Isolate and remove your clot.

  • Place an inferior vena cava (IVC) filter. This filter is placed into a large vein called the inferior vena cava to catch blood clots before they reach your lungs.

If you are taking blood thinners:

• Talk with your healthcare provider before you take any medicines that contain aspirin or NSAIDs. These medicines increase your risk for dangerous bleeding.

• Take your medicine exactly as instructed, at the same time every day. Do not skip a dose. Do not take more than the prescribed dose. This is important.

• Ask your healthcare provider about foods and medicines that could change or interact with the way your blood thinner works. Avoid these foods and medicines if you are told to do so.

• Avoid anything that may cause bleeding or bruising. You may bleed more easily while taking blood thinners.

  • Be very careful when using knives, scissors, or other sharp objects.

  • Use an electric razor instead of a blade.

  • Avoid activities that could cause injury or bruising, and follow instructions for preventing falls.

  • Tell your healthcare provider if you have had any internal bleeding, bleeding ulcers, or neurologic diseases, such as strokes or brain aneurysms.

• Wear a medical alert bracelet or carry a card that lists what medicines you take.

General instructions

• Take over-the-counter and prescription medicines only as instructed by your healthcare provider.

• Return to your normal activities as instructed by your healthcare provider. Ask your healthcare provider what activities are safe for you.

• If recommended, wear compression stockings as instructed by your healthcare provider. These stockings help to prevent blood clots and reduce swelling in your legs. Never wear your compression stockings while sleeping at night.

• Keep all follow-up appointments. This is important.

• Do not wait to see if the symptoms will go away.

• Do not drive yourself to the hospital.