A colonoscopy is a screening test that can find and remove polyps before colorectal cancer develops, or detect colorectal cancer at an early stage when it is easier to treat. For most people, a colonoscopy screening test is recommended once every 10 years.  However, a doctor may recommend colonoscopy screening more frequently for people considered at high risk, or for other medical reasons.


A colonoscopy is a procedure which is performed by a doctor who specializes in colonoscopy at a medical facility. Your family doctor or healthcare provider can refer you to a local facility to schedule this procedure. (Click Buffalo or Hastings for your local resources).



Preparing for a colonoscopy

  • The colon must be cleaned out so a doctor who specializes in colonoscopy can see the entire colon. All people are told to drink a large amount of liquid (the “prep”) the day before the procedure. The “prep” may cause frequent, urgent trips to the bathroom with loose, watery stools.
  • Some medications like blood thinners should be stopped before the procedure. Tell your doctor about the medications you are taking.
  • You will need someone to drive you home because you are sedated for the procedure.


How is the colonoscopy performed?

  • You are lightly sedated through a needle in your arm, which makes you sleepy and relaxed.
  • A narrow, flexible, lighted tube is inserted in the rectum to examine the entire colon to look for polyps.
  • Images of the inside of your colon are viewed by the doctor on a screen.
  • During the test the doctor can find and remove most polyps.
  • The actual procedure usually takes 20 to 40 minutes and the entire appointment could be around 2 to 3 hours.
  • After a colonoscopy, you need someone to drive you home and you may need to take the rest of the day off from normal activities.


Benefits of Colonoscopy Screening

Colonoscopy finds and removes most polyps so colorectal cancer can be prevented. If no polyps or cancer are found, the colonoscopy is only done once every 10 years.


During the colonoscopy, the doctor can see the entire colon and rectum. If a polyp is found during the test it can be removed before it turns into cancer. You are highly unlikely to get colorectal cancer if there are no polyps.


Colonoscopy is considered extremely accurate for detecting colorectal cancer. Less than 1 out of 100 people who have a colonoscopy will have a positive (abnormal) result when they do not have cancer.


Risks Associated with Colonoscopy

There are some risks associated with colonoscopy:

  • Less than 1 out of 1000 people who have colonoscopy have complications like bleeding or tearing the lining of the colon during the test.
  • Some people may have complications with the sedation used during the colonoscopy.
  • Colonoscopy might not detect small polyps, so it is possible that a negative result might have happened even if someone really does have a polyp.
  • There is the risk of a false negative or a false positive test result
    • False positive: when a screening test is positive (abnormal) when you actually do not have the disease
    • False negative: when a screening test is negative (normal) when you do have the disease


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