What is a colonoscopy?


What is the colon?



You will be given instructions in advance that will explain what you need to do to prepare for your colonoscopy. Your colon must be completely empty for the colonoscopy to be thorough and safe. To prepare for the procedure you will have to follow a liquid diet for 1 to 3 days beforehand. The liquid diet should be clear and not contain food colorings, and may include

  • fat-free bouillon or broth
  • strained fruit juice
  • water
  • plain coffee
  • plain tea
  • diet soda
  • gelatin

Thorough cleansing of the bowel is necessary before a colonoscopy. You will likely be asked to take a laxative the night before the procedure. In some cases you may be asked to give yourself an enema. An enema is performed by inserting a bottle with water and sometimes a mild soap in your anus to clean out the bowels. Be sure to inform your doctor of any medical conditions you have or medications you take on a regular basis such as

  • aspirin
  • arthritis medications
  • blood thinners
  • diabetes medication
  • vitamins that contain iron

The medical staff will also want to know if you have heart disease, lung disease, or any medical condition that may need special attention. You must also arrange for someone to take you home afterward, because you will not be allowed to drive after being sedated.


For the colonoscopy, you will lie on your left side on the examining table. You will be given pain medication and a moderate sedative to keep you comfortable and help you relax during the exam. The doctor and a nurse will monitor your vital signs, look for any signs of discomfort, and make adjustments as needed.


You may be asked to change positions at times so the doctor can more easily move the scope to better see the different parts of your colon. The scope blows air into your colon and inflates it, which helps give the doctor a better view. Most patients do not remember the procedure afterwards.

The doctor can remove most abnormal growths in your colon, like a polyp, which is a growth in the lining of the bowel. Polyps are removed using tiny tools passed through the scope. Most polyps are not cancerous, but they could turn into cancer. Just looking at a polyp is not enough to tell if it is cancerous. The polyps are sent to a lab for testing. By identifying and removing polyps, a colonoscopy likely prevents most cancers from forming.


During the procedure you may feel mild cramping. You can reduce the cramping by taking several slow, deep breaths. When the doctor has finished, the colonoscope is slowly withdrawn while the lining of your bowel is carefully examined. Bleeding and puncture of the colon are possible but uncommon complications of a colonoscopy.

A colonoscopy usually takes 30 to 60 minutes. The sedative and pain medicine should keep you from feeling much discomfort during the exam. You may feel some cramping or the sensation of having gas after the procedure is completed, but it usually stops within an hour. You will need to remain at the colonoscopy facility for 1 to 2 hours so the sedative can wear off.


For More Information

American College of Gastroenterology
P.O. Box 342260
Bethesda, MD 20827–2260
Phone: 301–263–9000
Fax: 301–263–9025
Email: info@acg.gi.org
Internet: www.acg.gi.org

International Foundation for Functional Gastrointestinal Disorders
P.O. Box 170864
Milwaukee, WI 53217–8076
Phone: 1–888–964–2001 or 414–964–1799
Fax: 414–964–7176
Email: iffgd@iffgd.org
Internet: www.iffgd.org