Understanding Colonoscopy Procedure

October 7, 2021by Health Desk

Why Would I Get a Colonoscopy?

A colonoscopy is the procedure used to examine the colon and the rectum. It uses a flexible fiber-optic instrument with camera on the end. It is a screening test to check for polyps or for cancer in the colon or rectum. Polyps are growths in the colon that might turn into cancer.

Other reasons for this test include blood in the bowel movements, change in the bowel habits, anemia, history of colon cancer or polyps in your colon.

Colonoscopy is also a diagnostic test in people who present with symptoms consistent with Inflammatory bowel disease.


How effective is a colonoscopy in detecting or preventing cancer?

While the colonoscopy is the gold standard test for detecting colon cancer, it has some limitations and shortcomings. Some studies show that colonoscopy is less effective in detecting cancer on the right side compared to the left side. Right-sided cancers can frequently evade detection since they are tucked into the folds of the intestines. At the same time, the benefits of a colonoscopy can be significant, so this limitation should not be a reason to avoid this test.

What are other benefits of a colonoscopy?

A colonoscopy is the only test that not only detects for polyps or cancer, but is also used to remove the polyp. This prevents polyps from possibly progressing to cancer.

Colonoscopy Removing Polyp

What are risks of colonoscopy procedures?

No procedure is without its risks, but the risks associated with a colonoscopy are very few. Rare complications include:

  • Bleeding from the site where the polyp was removed, or where the tissue sample (biopsy) was taken
  • A tear or perforation in the colon or rectum

When should I have colorectal cancer screening?

A regular screening is recommended by doctors beginning at age 45. Some people may begin screening at a younger age if they have a family history of colorectal cancer or certain medical conditions. Screening is generally done every 10 years or sometimes sooner to screen for colon cancer.

People with long-standing Inflammatory Bowel Disease (IBD) have an increased risk for colorectal cancer. Screening for colorectal cancer using a colonoscopy is generally done every 1-2 years with people who have had symptoms of IBD for 8 years or longer. Frequency of testing may be less than every 1-2 years, depending on the results of the previous colonoscopy.

How should I prepare for a colonoscopy?

Your doctor will give you instructions prior to the appointment. You might have to stop some medications up to a week prior to the test, as instructed by your doctor. Your doctor will also advise you on what foods and beverages to eat and avoid several days before the procedure.

To get a good look at the inside lining of the colon, the colon must be clean. You will be given a special drink that causes watery diarrhea before the procedure starts. It is important to drink all of it to clean your colon.

What happens during the colonoscopy?

The colonoscopy is performed in a hospital or clinic setting. To relax you before the procedure, your doctor can provide medication. A flexible fiber-optic instrument with camera on the end is inserted into the anus and up into the rectum and colon. The tube also has tiny tools on the end. The doctor uses it to examine the inside lining of the colon.

During the procedure, your doctor might take a small piece of tissue from the colon (biopsy). This tissue is examined under a microscope to detect any cancer. Your doctor may also remove growths if they are found in the colon.

What happens after colonoscopy?

After the colonoscopy, you will be instructed not drive or return to work for the rest of the day. Your doctor will provide instructions about other activities and precautions.

Colon cancer stages

What other tests are available for screening colorectal cancer?

The other screening tests for colorectal cancer are CT colonography, sigmoidoscopy, a stool test for blood, and a stool DNA test.

A CT colonography looks for cancer and polyps using CT scan technology. Cancers and polyps can bleed, and if they bleed at the time of the stool test, blood will show up on the test.

A sigmoidoscopy is similar to a colonoscopy, but it looks only at the last part of the colon. A colonoscopy looks at the whole colon.

The stool DNA test checks for genetic markers of cancer, as well as, for signs of blood.

Work with your doctor or nurse to decide which test is best for you. Some doctors might choose to combine screening tests.

To learn more about the colonoscopy procedure, watch the KnowYourMeds video:

Screening for Colon Cancer and the Role of Colonoscopies with Dr. Sanjiv Chopra and Dr. Frank Domino at https://knowyourmeds.com/know-your-health/