Having surgery can increase your risk of developing blood clots. But you may be able to prevent them with specific measures, including taking blood thinners and moving around.

A blood clot is a clump of platelets, proteins, and blood cells that has changed to a semi-solid state. Usually, when you get an injury like a cut, your body forms a blood clot to stop the bleeding. The blood clot naturally breaks down once it stops bleeding and your wound heals.

But sometimes blood clots form in places they shouldn’t. Your body can also make too many blood clots, and sometimes they don’t break down properly.

Deep vein thrombosis (DVT) happens when a blood clot forms in an important vein, typically causing pain and swelling. These clots can break off and travel to your heart and lungs, where they prevent blood flow — a medical emergency known as pulmonary embolism (PE).

Keep reading to understand how and why blood clots form and the steps you can take to prevent them.

Having surgery raises your risk of developing a blood clot. The location and type of surgery can affect your mobility during recovery, which may contribute to clots.

Other factors can increase your risk of developing a blood clot. These can include:

  • being unable to move around after surgery
  • being on bed rest
  • having overweight or obesity
  • smoking cigarettes
  • a family history of blood clots
  • having a blood clotting disorder

You can take some steps immediately before and after surgery to minimize your risk of developing blood clots.

How to help prevent blood clots before surgery

Some precautions you can take before surgery may help prevent blood clots from developing during recovery. These can include:

  • providing an accurate medical history so medical professionals understand your level of risk
  • making your care team aware of any medications or supplements you are taking, as some can affect your blood and make clots more likely
  • taking clot-dissolving medications (thrombolytics) if you have a high risk of DVT or PE

If your surgery is planned, you may be able to make specific lifestyle changes in advance to help lower your risk of blood clots. These can include:

If you have a high risk for clots, a doctor may request ultrasound scans to check for blood clots.

How to help prevent blood clots after surgery

Because having surgery raises your risk of developing blood clots, DVT, and PE, care teams typically recommend multiple steps to help prevent them. These can include:

  • improving your circulation with a compression device
  • elevating your arms and legs
  • wearing compression stockings
  • moving around as much as possible after surgery once a doctor has given permission
  • physical therapy after surgery, if needed
  • taking medication, such as blood thinners or aspirin

Depending on the type of surgery and individual circumstances, the doctor may prescribe blood thinners such as warfarin (Coumadin) or heparin. Doctors use blood thinners, or anticoagulants, to prevent unwanted blood clotting. They can also help keep any clots you currently have from getting bigger. Whether before or after surgery, the decision to administer blood thinners can be challenging because the surgeon has to weigh the risk of clot formation versus the risk of excessive bleeding due to the blood thinner.

Any type of surgery comes with some risks. Both DVT and PE are potential complications of surgery. If you experience symptoms of a blood clot, you may need emergency medical care. Symptoms may vary depending on the location of the blood clot.

Common symptoms of blood clots can include:

Clot locationSymptoms
Arm or legSudden or gradual pain in the limb
Warmth in the limb
HeartChest heaviness or pain
Arm numbness
Discomfort in other areas of the upper body
Shortness of breath
LungSharp chest pain
Racing heart or rapid breathing
Shortness of breath
Coughing up blood
BrainWeakness of the face, arms, or legs
Difficulty speaking or garbled speech
Vision problems
Sudden and severe headache
AbdomenSevere abdominal pain

Having surgery increases your risk for blood clots. According to the American Society of Hematology, as many as 900,000 people in the United States develop DVT each year.

It’s possible for clots to break off from a DVT and make their way to the heart, lungs, or brain, preventing adequate blood flow to these organs.

Surgery can increase your risk for blood clots for multiple reasons. These include:

Immobility during and after surgery

Muscle movement is needed to continuously pump blood to your heart. This inactivity causes blood to collect in the lower part of your body, generally, the leg and hip regions. This can lead to a clot.

Foreign matter in the bloodstream

Surgery also increases your risk for clots because the procedure can cause foreign matter to be released into your bloodstream, including tissue debris, collagen, and fat. When your blood comes into contact with foreign matter, it responds by thickening. This release can cause the blood to coagulate, or thicken.

Blood clotting in response to the procedure

Your body may also release naturally occurring substances that encourage blood clotting in response to bleeding that occurs during the procedure or removal or movement of organs and neighboring tissues during surgery.

Having surgery can raise your risk of developing a blood clot.

Doctors may evaluate your risk factors before surgery and make recommendations to prevent DVTs or PEs. These may include medication and monitoring. They may also recommend moving after surgery, once you can.

Blood clots can break off and travel to other organs. This can be life threatening. If you have symptoms of a blood clot, whether or not you have had surgery, you may need emergency medical attention.