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Preventing blood clots


Because you will be sitting or lying down for long periods of time during and after your surgery, your blood will move more slowly through your veins. General anesthesia also causes you blood to move more slowly through your veins. This increases the chance of blood clots forming in your leg veins (this is called deep vein thrombosis, or DVT).

People who have had a prior blood clot have a higher risk of developing another blood clot.

These clots may also form in the area where you just had surgery.

Blood clots in the legs (deep vein thrombosis)

Call your doctor right away if you have any of these symptoms. They are signs of a blood clot in your leg:

  • Red or blue skin color in your lower leg.
  • Calf pain in your leg. It may hurt to place all of your weight on this leg when you stand or move your ankle up and down.
  • Calf tenderness in your leg.
  • Swelling (edema) in your leg.

Blood clots in the lungs (pulmonary embolus)

Blood clots in the lungs (pulmonary embolus)

Blood clots that form in your legs can travel to your lungs. These clots can cause serious problems with your breathing. This condition is called a pulmonary embolism. Symptoms of a pulmonary embolism are:

  • Sharp chest pain
  • Difficult or fast breathing
  • Your heart will feel like it is racing
  • Coughing blood
  • Fainting
  • Sweating
  • Confusion

A blood clot that travels to your lungs is an emergency. Seek medical help or go to the closest emergency room right away if you have any of the above symptoms.

Preventing blood clots from forming

Before and after surgery, these things will help prevent blood clots from forming:

  • "Compression" stockings. You may be asked to wear these on your legs for a couple of weeks after surgery. They gently squeeze your legs to improve blood flow, and this helps prevent clots from forming.
  • Not smoking or using any other tobacco products. Tobacco restricts blood flow and can make a blood clot more likely to form.
  • Birth control pills. Women should talk with their surgeon if they use birth control pills, since they can make blood clots more likely to form.
  • Moving your ankles up and down. Your health care providers may show you how to do this to prevent clots from forming.
  • Getting up and moving around.

You may also need to take blood thinners for 3 to 4 weeks after your surgery to lower your risk of blood clots. Your doctor may prescribe one or both of these:

  • Shots under the skin that your provider will teach you to give yourself.
  • Pills that help prevent blood clots.
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Review Date: 12/31/2018

Reviewed By: C. Benjamin Ma, MD, Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery, San Francisco, CA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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