A colonoscopy is a visual examination of the entire large intestine, also known as the colon, and the lower part of the small intestine. This exam is used to explore possible causes of abdominal pain, rectal bleeding, chronic constipation, chronic diarrhea and other intestinal problems. A colonoscopy is also used as a method of screening for colon cancer. At test called sigmoidoscopy shows only the rectum and the lower part of the colon.

A gastroenterologist (GI) uses a thin, lighted, flexible tube called a colonoscope that has a small video camera attached to the tip, allowing the GI doctor to view the inside of the entire colon. GI doctors can also sample tissue and/or remove polyps in the colon during a colonoscopy. 

Men and women who are at average risk for colon caner are advised to schedule regular colonoscopies starting at age 50 (age 45 for African Americans), and continue to get a colonoscopy at 10-year intervals thereafter to screen for colon cancer. Patients who have a family history of colon cancer, have inflammatory diseases such as inflammatory bowel disorder (IBD) or other risk factors for colon cancer may be advised to be screened earlier or at an increased frequency.

Colonoscopy Checklist

One day before your colonoscopy

  • Eat breakfast – clear liquids only, no solid food
  • Eat lunch – clear liquids only, no solid food
  • Eat dinner – clear liquids only, no solid food
  • Take your bowel prep in the evening as instructed
  • Drink at least 12 glasses of clear liquid throughout the day

Day of your colonoscopy

  • If your doctor prescribed a “split prep,” take the second part of your bowel prep as instructed, starting 4 hours before your colonoscopy
  • Drink 2 tall glasses of clear sports drink prior to your appointment
  • Report to your appointment as instructed

Colonoscopy Advice 

Before your visit

Thorough cleansing of the entire bowel is essential for effective results so there will not be a need for retesting. Instructions for doing this will be given by your physician, but this can include a combination of the following: restrictions from eating solid foods a day or two before the test and taking liquid and/or pill-form laxatives. Colon prep takes 1 to 2 days, depending on which type of prep your doctor recommends. Some preps may be taken the evening before the test. For many people, the prep is worse than the test. The bowel prep may be uncomfortable, and you may feel hungry on the clear liquid diet. Plan to stay home during the prep time since you will need to use the bathroom often. The colon prep causes loose, frequent stools and diarrhea so that your colon will be empty for the test. If you need to drink a special solution as part of your prep, be sure to have clear fruit juices or soft drinks to drink after the prep because the solution may have a salty or unpleasant taste. The following recommendations are general guidelines. However, your physician may have varying instructions for your specific procedure. Please confirm the details of your prep instructions with your physician.

Your doctor will want to know if you have heart disease, lung disease or any other medical condition that may need special attention. Your physician may ask you to stop taking iron supplements several days before the test if you are on them. You may be asked to stop strong blood-thinning medications before the procedure as well. Check with your physician for exact instructions.

To avoid dehydration, patients should drink clear, fat-free bouillon or broth, gelatin, strained fruit juice (no grape juice or any liquid with red color) and water. Unless otherwise instructed, continue taking any regularly-prescribed medication.

Rubbing a small amount of hydrocortisone cream, such as Cort-Aid or something like Vaseline or A & D Ointment, around the anal area after each bowel movement can lessen the irritation. 

To improve flavor of the prep solutions, you may wish to add one or two packets of Crystal Light lemonade-flavored drink mix. Chill the solution in you refrigerator. Drink each glass quickly and, if needed, it is sometimes helpful to hold your nose and use a straw to lessen your ability to taste the solution. Sucking on lime or hard candy between glasses can also help.

Finally, you need to arrange for someone to drive you home after your procedure because lingering, subtle effects of the sedation will make it unsafe for you to drive until the next day.

Day of visit

Typically, intravenous (IV) sedation is used during a colonoscopy. When it’s time to start the examination, you will be asked to lie on your left side. Once sedation takes effect, the colonoscope is inserted through the rectum and moved gently around the bends of the colon. As the colonoscope makes its way through the colon, the physician can see the lining of the colon on a television screen. Typically, the physician looks all the way to the end of the large intestine and back for anything unusual. The scoping process generally takes approximately 30 minutes.

After you procedure, you nurse will take you into a recovery area, where the sedation quickly wears off. Your physician will talk to you about your test and any findings.

After your visit

Recovery time is usually 30 minutes to an hour, depending on the type and amount of sedation you receive. After the exam, you may have mild abdominal discomfort. You may feel bloated or pass gas for a few hours as you clear the air from your colon. You may have a small amount of blood in your stool with your first bowel movement after the procedure. This is normal. Call your doctor if this continues or you have persistent abdominal pain or a fever of 100 degrees Fahrenheit or higher. 

You will need someone to drive you home because it can take up to a day for the full effects of the sedative to wear off. You should be able to resume normal activity the next day. Be sure to ask your doctor when you can resume taking any medications you had to stop taking before the colonoscopy. 

Your doctor will talk to you when you are awake and go over the results with you. If a biopsy was taken, your doctor will do a follow-up to let you know the results. If a polyp was removed during your colonoscopy, your doctor may recommend having a follow-up colonoscopy in as little as three months depending on the size and number of polyps found. If no polyps were found, your next colonoscopy will need to be in 10 years, or sooner depending on your family history and other factors.

Test Findings

Possible findings include diverticulosis and polyps. If polyps (growths of tissue) are found, they will be removed during the colonoscopy and sent to a pathologist.

Polyps are small growths in the lining of the colon. They are common and there are different types such as benign and cancerous polyps. While the overwhelming majority of polyps are benign, your physician will have it tested and will contact you to confirm the lab results as soon as they are ready.

Alternatives to Colonoscopy

Two alternatives to colonoscopy are available. One is a barium enema study that is an X-ray evaluation using a dye that shows up on radiological film. It is not as accurate as a colonoscopy, since it is not a direct evaluation and the results are determined not in real time but read later by a radiologist. The other test is a flexible sigmoidoscopy. This is a limited study with a shorter scope and examines only the last third of the colon nearest to the rectum.