Preparing For a Colonoscopy

Learn the Importance of Properly Preparing for a Colonoscopy Exam

Woman doctor talking to patient in hospital
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If your signs and symptoms indicate that you could have colon cancer, your doctor may tell you to begin preparing for a colonoscopy. 

Colon cancer is cancer of the large intestine (colon), the lower part of your digestive system. Most cases of colon cancer begin as small, noncancerous (benign) clumps of cells called adenomatous polyps. Over time some of these polyps become colon cancers. Polyps may be small and produce few, if any, symptoms.

For this reason, doctors recommend regular screening tests, such as a colonoscopy, to help prevent colon cancer by identifying polyps before they become colon cancer.

Preparing For Colonoscopy

To prepare for a colonoscopy, you will need to clear everything out of your colon. As you might have guessed, this means taking laxatives and possibly giving yourself an enema to remove all stool before the colonoscopy.

This is the most important part of colonoscopy preparation. If your colon is not completely empty, the doctor will not be able to see your colon clearly. He or she could miss adenomas and polyps – the small growths that need to be removed to reduce the risk of later developing colon cancer – or other signs of cancer.

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Steps to Take One Day Before Colon Cancer Screening

What to Expect on the Day of Colon Cancer Screening

If you've been diagnosed with colon cancer, your doctor will order additional tests to determine the extent (stage) of your cancer. Staging helps determine what treatments are most appropriate for you. Staging tests may include imaging procedures such as abdominal and chest CT scans.

In many cases, the stage of your cancer may not be determined until after colon cancer surgery.

The stages of colon cancer are:

  • Stage I. Your cancer has grown through the superficial lining (mucosa) of the colon or rectum but hasn't spread beyond the colon wall or rectum.
  • Stage II. Your cancer has grown into or through the wall of the colon or rectum but hasn't spread to nearby lymph nodes.
  • Stage III. Your cancer has invaded nearby lymph nodes but isn't affecting other parts of your body yet.
  • Stage IV. Your cancer has spread to distant sites, such as other organs — for instance to your liver or lung.


Gastroenterology of the Rockies Colonoscopy Pep Talk. Accessed: January 29, 2009.

The American Cancer Society Frequently Asked Questions About Colonoscopy and Sigmoidoscopy. Accesed: January 29, 2009.

WikiHealth How to Prepare for a Colonoscopy. Accessed: January 29, 2009.

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