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A colonoscopy is an exam of the large intestine, also known as the colon. The exam is done with a tool called a colonoscope. The colonoscope is a flexible tube with a tiny camera on the end. This tool allows the doctor to view the inside of your colon.
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Reasons for Procedure
A colonoscopy is used to examine, diagnose, and treat problems in your colon. The procedure is most often done to:
Complications are rare, but no procedure is completely free of risk. If you are planning to have a colonoscopy, your doctor will review a list of possible complications, which may include:
- Colon perforation
Factors that may increase the risk of complications include:
- Pre-existing heart or kidney condition
- Treatment with certain medications, including aspirin and other drugs with blood-thinning properties
- Prior abdominal surgery
- Active colitis, diverticulitis, or other acute bowel disease
- Previous treatment with radiation therapy
Be sure to discuss these risks with your doctor before the procedure.
What to Expect
Prior to Procedure
Your doctor will likely do the following:
- Perform a physical exam
- Review your health history
- Review any medication you are taking
- Test your stool for blood
Talk to your doctor about your medications. You may be asked to stop taking some medications up to one week before the procedure.
On the day of the procedure:
- Wear comfortable clothing.
- Arrange for a ride home after the procedure.
Emptying the Colon
Your colon must be completely clean before the procedure. Any stool left in the colon will block the view. This preparation may start several days before the procedure. Follow your doctor's instructions, which may include any of the following cleansing methods:
- Enemas—fluid introduced into the rectum to stimulate a bowel movement
- Laxatives—medications that cause you to have soft bowel movements
- Oral cathartic medications—a fluid you drink to help stimulate a bowel movement
For the entire day before your procedure:
- Do not eat any solid foods. This includes milk or cream in your coffee.
- Drink only clear liquids such as water, coffee without cream, ginger ale, apple juice, and sports drinks (do not drink red sports drinks)
- You can also have gelatin or popsicles as long as they are not red
- Do not drink alcohol
- If you have diabetes, ask your doctor if you need to adjust your insulin dose
Your doctor may give you medication to help you relax. You'll probably feel sleepy.
Description of the Procedure
You will lie on your left side. Your knees will be drawn up toward your chest. The colonoscope will be slowly inserted through the rectum. The colonoscope will inject air into the colon. The doctor will be able to see the lining of the colon with a small video camera on the colonoscope. The colonoscope will be gently passed through the colon to view the entire area.
A tissue sample or polyps may be removed during the procedure. This is done with small tools passed through the colonoscope.
How Long Will It Take?
Less than one hour
Will It Hurt?
Most people report some discomfort when the instrument is inserted. You may also feel some cramping or lower abdominal pain during the procedure. Medication will help decrease discomfort, some will sleep through the procedure.
After the procedure, gas pains and cramping are common. These pains should go away with the passing of gas.
If any tissue was removed:
- It will be sent to a lab to be examined. It may take 1-2 weeks for results. The doctor can usually give an initial report after the scope is removed. Other tests may be advised.
- A small amount of bleeding may occur during the first few days after the procedure.
Call Your Doctor
It is important to monitor your recovery. Alert your doctor to any problems. If any of the following occur, call your doctor:
- Bleeding from your rectum—Notify your doctor if you pass a teaspoonful of blood or more.
- Black, tarry stools
- Severe abdominal pain
- Hard, swollen abdomen
- Signs of infection, including fever or chills
- Inability to pass gas or stool
- Coughing, shortness of breath, chest pain, severe nausea or vomiting
If you think you have an emergency, call for emergency medical services right away.
American Society for Gastrointestinal Endoscopy
National Institute of Diabetes and Digestive and Kidney Diseases
American Gastroenterological Association
American Society for Gastrointestinal Endoscopy
Canadian Association of Gastroenterology
Canadian Digestive Health Foundation
Colonoscopy. EBSCO DynaMed Plus website. Available at:http://www.dynamed.com/topics/dmp~AN~T114112/Colonoscopy. Updated March 21, 2017. Accessed October 3, 2017.
Colonoscopy. National Institute of Diabetes and Digestive and Kidney Diseases website. Available at: https://www.niddk.nih.gov/health-information/diagnostic-tests/colonoscopy. Updated July 2017. Accessed October 3, 2017.
Frequently asked questions about colonoscopy and Sigmoidoscopy. American Cancer Society website. Available at: https://www.cancer.org/treatment/understanding-your-diagnosis/tests/faq-colonoscopy-and-sigmoidoscopy.html. Updated February 2, 2016. Accessed October 3, 2017.
6/2/2011 DynaMed's Systematic Literature Surveillancehttp://www.dynamed.com/topics/dmp~AN~T905141/Treatment-for-tobacco-use: Mills E, Eyawo O, Lockhart I, Kelly S, Wu P, Ebbert JO. Smoking cessation reduces postoperative complications: a systematic review and meta-analysis. Am J Med. 2011;124(2):144-154.
Last reviewed September 2018 by EBSCO Medical Review Board Daus Mahnke, MD Last Updated: 8/9/2017