How Safe are Colonoscopies?

Colonoscopies are one of the best ways to screen for colon cancer – but are they really safe? Find out what the chances are of experiencing a complication from a colonoscopy.

Not enough people are getting screening colonoscopies. Most doctors recommend that people at average risk for colon cancer undergo this procedure after the age of fifty to look for precancerous polyps and signs of colon cancer – and people at high risk, even earlier. Why aren’t more people doing it? Some hesitate to get the procedure because they can’t stomach the mandatory bowel prep, while others have concerns about the safety of the procedure. Are colonoscopies safe?

Are Colonoscopies Safe?

It’s hardly surprising have reservations about having a tube inserted into their colon. On the other hand, screening colonoscopies save lives by picking up pre-cancerous polyps and tumors that would otherwise grow, spread, and eventually lead to death.

The risk of complications from getting a screening colonoscopy is low. One of the most serious risks is getting a perforation or tear in the intestinal wall – a complication that can be life threatening – and requires immediate surgery. The risk of this happening depends is at least partially dependent upon the skill of the doctor – and may be as high as one in 140 cases to as low as one in around 3,500 procedures. The average rate of intestinal perforation during a colonoscopy is about one in every 500 to 1,000 colonoscopies.

Another risk of a screening colonoscopy is the possibility of heavy bleeding which can occur during or after the procedure. When bleeding occurs during the procedure, it can usually be quickly cauterized. The risk of this happening varies from one in about 40 cases to one in 500. There are also other complications such as the potential for bowel infection, but these are rare.

What about the ultimate bad outcome from a screening colonoscopy – death? Fortunately, this only happens in one in 3,000 to one in 30,000 colonoscopies.

Are Colonoscopies Safe? Consider the Up Side

A screening colonoscopy can be lifesaving by detecting precancerous colon polyps that would eventually develop into cancer and allow them to be removed before they have a chance to become malignant. This procedure can also pick up early colon cancers before they cause symptoms. Colon cancers that are still confined to the bowel wall can be cured with surgery.

The Bottom Line?

A screening colonoscopy, like most invasive procedures, isn’t risk free, but the chance of developing a serious complication is small. One way to reduce the risk is to have a colonoscopy done only by a gastroenterologist who does the procedure on a daily basis. Some internists and family practitioner’s undergo training courses to do colonoscopies, but they may not have the chance to do as many procedures. All in all, for most people, a screening colonoscopy to pick up colon cancer early is worth the small risk.


J Natl Cancer Inst. 2003 Feb 5;95(3):230-6.

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