Information about colonoscopy

A colonoscopy is an outpatient procedure in which the inside of the large intestine (colon and rectum) is examined. A colonoscopy is commonly used to evaluate gastrointestinal symptoms, such as rectal and intestinal bleeding, or changes in bowel habits. Colonoscopies are also performed for colorectal cancer screening in individuals without symptoms to check for colorectal polyps or cancer. A screening colonoscopy is recommended for anyone 50 years of age and older (45 for African Americans), and for anyone with parents, siblings, or children with a history of colorectal cancer or polyps.

Normal Colon

Normal Colon

Clean Colon

Clean Colon

Dirty Colon

Dirty Colon

What happens before a colonoscopy?

To have a successful colonoscopy, your bowel must be empty so that your doctor can clearly view the colon. To do this, it is very important to read and follow all of the instructions given to you at least 2 weeks BEFORE your exam. If your bowel is not empty, your colonoscopy will not be successful and may have to be repeated.

If you feel nauseated or vomit while taking the bowel preparation, wait 30 minutes before drinking more fluid and start with small sips of solution. Some activity (such as walking) or a few soda crackers may help decrease the nausea you are feeling. If the nausea persists, call your doctor.

You may experience skin irritation around the anus due to the passage of liquid stools. To prevent and treat skin irritation, you should:

  • Apply vaseline or Desitin® ointment to the skin around the anus before drinking the bowel preparation medications. These products can be purchased at any drug store.
  • Wipe the skin after each bowel movement with disposable wet wipes instead of toilet paper. These are found in the toilet paper area of the store.
  • Sit in a bathtub filled with warm water for 10 to 15 minutes after you finish passing a stool. After soaking, blot the skin dry with a soft cloth. Then apply vaseline or Desitin® ointment to the anal area, and place a cotton ball just outside your anus to absorb leaking fluid.

What happens during a colonoscopy?

During a colonoscopy, an experienced doctor uses a colonoscope (a long, flexible instrument about 1/2 inch in diameter) to view the lining of the colon. The colonoscope is inserted into the rectum and advanced through the large intestine. If necessary during a colonoscopy, small amounts of tissue can be removed for analysis (a biopsy) and polyps can be identified and entirely removed. In many cases, a colonoscopy allows accurate diagnosis and treatment of colorectal problems without the need for a major operation.

  • You are asked to wear a hospital gown and an IV will be started.
  • You are given a pain reliever and a sedative intravenously (in your vein). You will feel relaxed and somewhat drowsy.
  • You will lie on your left side, with your knees drawn up towards your chest.
  • A small amount of air is used to expand the colon so the physician can see the colon walls.
  • You may feel mild cramping during the procedure. Cramping can be reduced by taking slow, deep breaths.
  • The colonoscope is slowly withdrawn while the lining of your bowel is carefully examined.
  • The procedure lasts from 30 minutes to 1 hour.

What happens after a colonoscopy?

  • You will stay in a recovery room for observation until you are ready for discharge.
  • You may feel some cramping or a sensation of having gas, but this quickly passes.
  • If sedation has been given, a responsible family member or friend must drive you home.
  • The procedure typically lasts from 30 minutes to 1 hour.
  • Avoid alcohol, driving, and operating machinery for 24 hours following the procedure.
  • Unless otherwise instructed, you may immediately return to your normal diet. We recommend you wait until the day after your procedure to resume normal activities.
  • If polyps were removed or a biopsy was taken, the doctor performing your colonoscopy will tell you when it is safe to resume taking your blood thinners.
  • If a biopsy was taken or a polyp was removed, you may notice light rectal bleeding for one to two days after the procedure. If you have a large amount of rectal bleeding, high or persistent fevers, or severe abdominal pain within the next 2 weeks, go to your local emergency room and call the physician who performed your exam.

Colonoscopy Instructions

Sedation for Colonoscopy

Sedation for colonoscopy can be done by two different methods. One is called Conscious Sedation and the other is called General Anesthesia. Both types of sedation may result in patients not recalling the procedure or sleeping through all or part of the exam. In order to prepare yourself for your colonoscopy, you should follow the bowel preparation instructions listed below by the type of sedation (conscious sedation or general anesthesia) recommended by the physician who ordered your procedure.

Conscious Sedation

Conscious Sedation is managed by the physician performing your procedure and is performed on main campus and Cleveland Clinic Health System regional facilities.

General Anesthesia

General Anesthesia is managed by an anesthesiologist or Certified Registered Nurse Anesthetists (CRNA) and is performed on main campus in Q3 only.


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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 3/22/2017...#4949