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The purpose of a colonoscopy is to examine the inside of the colon for cancer, polyps,  inflammation or other abnormalities.  The procedure uses a colonoscope which is a thin, flexible tube with a light that sends images to a monitor.  A tissue sample or polyp can be removed with the colonoscope.

Specific preparation instructions are required the day before your procedure.  General preparation instructions are listed below.  Your doctor may have a specific preparation that they would like you to follow.  Your doctor will let you know what their specific instructions are.

Learn more about colonoscopy.


Polyethylene Glycol Bowel Prep

Brand names include  Co-lyte, Tri-lyte and Halflytely

The day before your colonoscopy:

  1. Eat a clear liquid diet for for breakfast, lunch and dinner.  Clear liquids are anything you can see through.  This includes clear water, fat free broths, tea, Jell-O and Gatorade.  For more information please see FAQ.
  2. Add water to the jug of prep solution to the “fill here line” and mix until the powder in the jug has dissolved.  You can mix this earlier and place in the refrigerator to make it more palatable.
  3. At approximately 8 AM take 2 Dulcolax (bisacodyl) tablets with 8 ounces of water.
  4. Between noon and 5 pm drink an 8 ounce glass of prep every 10-15 minutes until 3/4 of the solution is gone.  Save and refrigerate the rest of the solution.  Your stool should eventually be a clear yellow color and you should be able to see the bottom of the toilet after prepping.
  5. You may continue to drink clear liquids throughout the evening.

The day of your colonoscopy:

  1. Do not eat breakfast or any food, drink, candy, gum, chewing tobacco and do not smoke for at least 3 hours before your procedure.
  2. You may take your medication with a sip of water.
  3. At least 4 hours before your appointment, drink the remainder of the saved prep.  You must have finished the final glass at least 3 hours before your check in time.


Instructions related to medication:

  • stop taking iron supplements at least 3 days before your procedure
  • if you are a diabetic on insulin please check with our primary doctor about any changes needed in your dose the day of the procedure
  • if you are on a blood thinning medication please let us know when your procedure is scheduled.  These medications often need to be stopped prior to the procedure