Blood Clots During and After Surgery

Surgeon reaching for surgical scissors in operating room

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Blood clots are a concerning complication that you may face during and after surgery.

While a blood clot that forms in the leg can be a dangerous condition, blood clots can quickly become life-threatening. These complications are very serious and must be treated quickly to minimize the damage to your body.


Common Causes & Risk Factors for Blood Clots


A blood clot is more likely to form during or after surgery than it is during your routine day-to-day life. There are multiple reasons for this, but one major cause is inactivity.

Inactivity makes it easier for blood to clot because muscle use typically squeezes blood out of your veins and keeps it from pooling. Pooling blood can lead to clots.

During surgery, you lie still on the operating table for an extended period of time, which puts you at risk for clots.

Many people are also inactive after surgery because they’re in pain, sick, or unable to walk. That increases the risk of clot formation after the procedure.

The type of surgery you are having can increase the risk of having blood clots after the procedure as well. If your surgery requires your arteries or veins to be cut or repaired, the risk of a blood clot is higher because your body works to stop bleeding by forming clots.

If you’re having a surgery where your heart is stopped, typically a heart bypass surgery (CABG), your risk of a blood clot is also increased.

Your medical and social history may contribute to clot formation. For example, if you’re a smoker, you’re at higher risk for the formation of blood clots than the average person, even without having surgery.

Risk Factors

A wide range of medical conditions and other factors can increase your risk of post-surgical blood clots. These conditions include:

  • Atrial fibrillation (irregular heartbeat)
  • Pregnancy, as clotting speed increases in preparation for childbirth
  • Some types of cancer that make blood clot more easily
  • History of blood clots
  • Family history of blood clots
  • Hormone replacement therapy
  • Smoking
  • Obesity
  • Prolonged Immobility
  • Heart valve issues
  • Dehydration


Getting up and moving during your recovery from surgery is one of the best ways to prevent blood clots. Staying well hydrated by drinking ample amounts of water can also reduce your risk of forming clots.

In addition to these simple measures, your healthcare provider may prescribe medication to prevent clots from forming. As always, prevention is better than treatment. 

Injectable medications—such as Lovenox or Heparin—are very common during a hospital stay after surgery. This medication is given to prevent the formation of a blood clot. It is less commonly prescribed for use at home. 


The treatment for blood clots depends on their location. The drug Coumadin (warfarin) helps the body remove a clot from the bloodstream. Heparin may also be given to prevent additional clots from forming or to prevent clots from getting bigger.

Clots that form in the legs are called deep vein thrombosis (DVT) and are the most common type of blood clot after surgery. They have a variety of causes and typically remain in the legs, but can break free and move through the bloodstream.

Clots can move from the legs to the lungs and cause a life-threatening condition called a pulmonary embolism. While a pulmonary embolism can be treated, it’s associated with a high mortality rate.

Typically, clots in the legs are treated with medication, but if there’s a high risk of the clot moving to the lungs or you can’t safely take the medication, a device called an inferior vena cava filter may be placed. This device acts as a tiny basket, catching clots before they can lodge in the lungs and cause damage.

A healthcare provider places these filters through a small incision in the groin or neck, then threads the filter into place in the inferior vena cava (a large vein). The filter may be in place temporarily or permanently.

A Word From Verywell

Blood clots after surgery can be a very serious complication. If you experience unexplained pain or a dramatic increase in pain after surgery, particularly in the legs, there could be an issue with blood clots.

It’s far better to report the possibility of a blood clot to your healthcare provider than to ignore it and experience a life-threatening issue such as a pulmonary embolism. 

After surgery, safe is always better than sorry, especially when blood clots are a possibility.

Blood Clots Healthcare Provider Discussion Guide

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2 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Heart Lung and Blood Institute. Venous thromboembolism.

  2. Agency for Healthcare Research and Quality. Your guide to preventing and treating blood clots.

By Jennifer Whitlock, RN, MSN, FN
Jennifer Whitlock, RN, MSN, FNP-C, is a board-certified family nurse practitioner. She has experience in primary care and hospital medicine.