Colonoscopy

How to Prepare for the Test

Your bowel needs to be completely empty and clean for the exam. A problem in your large intestine that needs to be treated may be missed if your intestines are not cleaned out.

Your health care provider will give you the steps for cleansing your bowel. This is called bowel preparation. Steps may include:

• Using enemas
• Not eating solid foods for 1 to 3 days before the test
• Taking laxatives

You need to drink plenty of clear liquids for 1 to 3 days before the test. Examples of clear liquids are:

• Clear coffee or tea
• Fat-free bouillon or broth
• Gelatin
• Sports drinks without added color
• Strained fruit juices
• Water

You will likely be told to stop taking aspirin, ibuprofen, naproxen, or other blood-thinning medicines for several days before the test. Keep taking your other medicines unless your doctor tells you otherwise.

You will need to stop taking iron pills or liquids a few days before the test, unless your provider tells you it is OK to continue. Iron can make your stool dark black. This makes it harder for the doctor to view inside your bowel.

How the Test will Feel

The medicines will make you sleepy so that you may not feel any discomfort or have any memory of the test.

You may feel pressure as the scope moves inside. You may feel brief cramping and gas pains as air is inserted or the scope advances. Passing gas is necessary and should be expected.

After the exam, you may have mild abdominal cramping and pass a lot of gas. You may also feel bloated and sick to your stomach. These soon go away.

You should be able to go home 1 hour after the test. You must plan to have someone take you home after the test, because you will be woozy and unable to drive. The providers will not let you leave until someone arrives to help you.

When you are home, follow instructions on recovering from the procedure. These may include:

• Drink plenty of liquids. Eat a healthy meal to restore your energy.
• You should be able to return to your regular activities the next day.
• Avoid driving, operating machinery, drinking alcohol, and making important decisions for at least 24 hours after the test.

Why the Test is Performed

Colonoscopy may be done for the following reasons:

• Abdominal pain, changes in bowel movements, or weight loss
• Abnormal changes (polyps) found on sigmoidoscopy or x-ray tests (CT scan or barium enema)
• Anemia due to low iron (usually when no other cause has been found)
• Blood in the stool, or black, tarry stools
• Follow-up of a past finding, such as polyps or colon cancer
• Inflammatory bowel disease (ulcerative colitis and Crohn disease)
• Screening for colorectal cancer

Normal Results

Normal findings are healthy intestinal tissues.

What Abnormal Results Mean

Abnormal test results may mean any of the following:

• Abnormal pouches on the lining of the intestines, called diverticulosis
• Areas of bleeding
• Cancer in the colon or rectum
• Colitis (a swollen and inflamed intestine) due to Crohn disease, ulcerative colitis, infection, or lack of blood flow
• Small growths called polyps on the lining of your colon (which can be removed through the colonoscope during the exam)

Risks

Risks of colonoscopy may include any of the following:

• Heavy or ongoing bleeding from biopsy or removal of polyps
• Hole or tear in the wall of the colon that requires surgery to repair
• Infection needing antibiotic therapy (very rare)
• Reaction to the medicine you are given to relax, causing breathing problems or low blood pressure

References

Chernecky CC, Berger BJ. Colonoscopy - diagnostic. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. Philadelphia, PA: Elsevier Saunders; 2013:358-359.

Itzkowitz SH, Potack J. Colonic polyps and polyposis syndromes. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease: Pathophysiology/Diagnosis/Management. 10th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 126.

Lieberman DA, Rex DK, Winawer SJ, et al. United States Multi-Society Task Force on Colorectal Cancer. Guidelines for colonoscopy surveillance after screening and polypectomy: a consensus update by the US Multi-Society Task Force on Colorectal Cancer. Gastroenterology. 2012;143:844-857. PMID: 22763141 www.ncbi.nlm.nih.gov/pubmed/22763141.

National Comprehensive Cancer Network. NCCN clinical practice guidelines in oncology: colorectal cancer screening. Version 1.2015. www.nccn.org/professionals/physician_gls/pdf/colorectal_screening.pdf. Accessed February 11, 2016.