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A colonoscopy is an exam of the colon. The exam is done with a long, thin tube called a scope. This scope has a tiny camera on the end which allows the doctor to see the walls of the colon.


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Reasons for Procedure

The colon is the last part of your intestines. A colonoscopy is used to look for and treat problems in the area. The most common reasons for a colonoscopy are to:

  • Look for cause of belly pain, bleeding, or problems with passing stool
  • Look for signs of colon cancer; may also be a part of treatment
  • Look for and remove colon polyps; some polyps can become cancer
  • Take sample of colon to look at under a microscope (known as a biopsy)
  • Stop bleeding in the colon
  • See if treatment for inflammatory bowel disease is working as it should

Possible Complications

Problems are rare, but all procedures have some risk. Your doctor will talk to you about possible problems such as:

The risk of problems is increased with:

  • Smoking
  • Heart or kidney problems
  • Treatment with certain medicine, including aspirin and other blood-thinning drugs
  • Prior surgery in the area
  • Active colitis, diverticulitis, or other acute bowel disease
  • Radiation therapy in the past

What to Expect

Call Your Doctor

Let your doctor know if recovery is not going as expected or you have any of the following:

  • Bleeding from your rectum—more than your doctor said you may see
  • Black, tarry stools
  • Severe belly pain
  • Hard, swollen belly
  • Signs of infection, including fever or chills
  • Problems passing gas or stool
  • Coughing, shortness of breath, chest pain, severe nausea or vomiting

If you think you have an emergency, call for emergency medical services right away.







  • Colonoscopy. EBSCO DynaMed website. Available at: http://www.dynamed.com/topics/dmp~AN~T114112/Colonoscopy .
  • Colonoscopy. National Institute of Diabetes and Digestive and Kidney Diseases website. Available at: https://www.niddk.nih.gov/health-information/diagnostic-tests/colonoscopy.
  • National Cancer Institute. Colon cancer treatment (PDQ®)-patient version website. https://www.cancer.gov/types/colorectal/patient/colon-treatment-pdq#link/_93 NIH external link.
  • 6/2/2011 DynaMed's Systematic Literature Surveillance http://www.dynamed.com/topics/dmp~AN~T905141/Treatment-for-tobacco-use : Mills E, Eyawo O, Lockhart I, Kelly S, Wu P, Ebbert JO. Smoking cessation reduces postoperative complications: a systematic review and meta-analysis. Am J Med. 2011;124(2):144-154.


  • Mark Arredondo, MD
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.