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CancerQuest > Introduction to Patient Information > Introduction to Cancer Detection and Diagnosis > Colonoscopy: Introduction > Colonoscopy: Preparation

Colonoscopy: Preparation

In order for a colonoscopy to be effective and accurate, the colon must be extremely clean so that the colonoscope can navigate through without being blocked by stool. There must not be any solids or liquids present that could obscure the view of the camera. What a patient does the days preceding the exam can directly affect how well the colon can be examined. To prepare for the procedure, most patients will be asked to do the following:

• Discontinue use of iron pills or other medications containing iron because iron can change the color of the colon lining.
• Take laxatives and enemas that are prescribed by their doctors. The bowel movements caused by these treatments clear the bowel and make the imaging process easier.
• While drinking the laxative, take a 5 minute walk every 10 minutes
• Avoid eating solid foods and opaque liquids
• Drink only clear liquids such as black coffee, tea, water, clear broth, and juices without pulp. Eat only soft foods such as JELL-O®, but nothing that is red in color, since it can affect the colon lining.

On the day of the exam, the patient may be asked to not eat at all, or restricted to a diet of only clear, non-alcoholic liquids. Patients who have diabetes or are taking blood thinners may have different guidelines that they should follow and should consult their physicians for specific instructions about pre-exam preparation.

In rare cases, the phosphate-based laxative has caused kidney damage in healthy older adults, people taking medication for hypertension, arteriosclerosis, or heart disease, and those with chronic kidney disease. Patients who are in one of these categories may be given a special type of cleansing solution.^{(1) (2)}

Patients should wear loose, comfortable, casual clothing that can be easily removed because most likely, a gown will be provided. Patients should also leave their jewelry and valuables at home.⁽³⁾

References for this page:

1. JD Waye. "Colonoscopy". CA: A Cancer Journal for Clinicians. 1992;42(6):350-65. [PUBMED]
2. "Colonoscopy." Mayo Clinic [http://www.mayoclinic.com/health/colonoscopy/CO00009 ]
3. "Colonoscopy." Three Rivers Endoscopy Center [http://www.gihealth.com/html/test/colonoscopy.html ]