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Home > Health Library > Colonoscopy
Colonoscopy is a test that allows your doctor to look at the inner lining of your large intestine (rectum and colon). Your doctor uses a thin, flexible tube called a colonoscope to look at the colon. A colonoscopy helps find ulcers, colon polyps, tumors, and areas of inflammation or bleeding. During the test, tissue samples can be collected (biopsy) and abnormal growths can be taken out. Colonoscopy can also be used as a screening test to check for cancer or precancerous growths in the colon or rectum (polyps).
A colonoscopy looks at the whole colon and the lower part of the small intestine. A test called sigmoidoscopy shows only the rectum and the lower part of the colon.
Before this test, you will need to clean out your colon (colon prep). 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. If your doctor ordered a split prep, you'll do part of the prep the evening before and the other part on the day of the test. Plan to stay home during your 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.
Colonoscopy is one of the many tests that may be used to screen for colon cancer. Other tests include stool tests, sigmoidoscopy, and CT colonography. Which screening test you choose depends on what you prefer. Talk to your doctor about what puts you at risk and what test is best for you.
Colonoscopy may be done to:
Procedures can be stressful. This information will help you understand what you can expect. And it will help you safely prepare for your procedure.
A colonoscopy may be done in a doctor's office, clinic, or a hospital.
During the test, you may get a pain medicine and a sedative put in a vein in your arm (IV). These medicines help you relax and feel sleepy during the test. You may not remember much about the test.
You will need to take off most of your clothes. You will be given a gown to wear during the test.
You may lie on your left side with your knees pulled up to your belly. Because you will be given medicine during the colonoscopy, you probably won't remember having the test when you wake up.
Next, the doctor will insert a thin, flexible colonoscope in your anus and move it slowly through the rectum and into your colon. Air will be used to inflate your colon so the doctor can see the lining of the colon on a monitor.
Your doctor will look at the whole length of your colon as the scope is gently moved in and then out of your colon. You may be asked to change your position during the test.
The doctor may also collect tissue samples (biopsy) or take out growths. Usually, people don't feel anything if a biopsy is done or if polyps are taken out.
The scope is slowly pulled out of your anus, and the air escapes. Your anal area will be cleaned with tissues. If you are having cramps, passing gas may help relieve them.
After the test, you'll stay at the clinic until you wake up and then have a brief visit from your doctor. Then you'll be allowed to leave with the person who will drive you home.
The test usually takes 30 to 45 minutes. But it may take longer, depending upon what is found and what is done during the test.
The colon prep will cause diarrhea. Some people also have cramping.
During the test, you may feel very sleepy and relaxed from the sedative and pain medicines. Many people say that they don't remember very much about the test because of the sedative.
You will feel sleepy after the test for a few hours.
There is a small chance for problems from a colonoscopy. The scope may tear the colon or cause bleeding.
If a sample of tissue (biopsy) was collected during the colonoscopy, it will be sent to a lab for tests.
Your doctor may be able to tell you the results right after the procedure. Other test results are ready in 2 to 4 days. Test results for certain infections may be ready in several weeks.
The lining of the colon looks smooth and pink, with a lot of normal folds. No growths, pouches, bleeding, or inflammation are seen.
Some abnormal findings of colonoscopy include hemorrhoids (the most common cause of blood in the stool), polyps, cancer, one or more sores (ulcers), pouches in the wall of the colon (diverticulosis), and inflammation. A red, swollen lining of the colon (colitis) may be caused by infection or inflammatory bowel disease (IBD).
Current as of:
December 17, 2020
Author: Healthwise StaffMedical Review: Adam Husney MD - Family MedicineE. Gregory Thompson MD - Internal MedicineKathleen Romito MD - Family MedicineArvydas D. Vanagunas MD - Gastroenterology
Current as of: December 17, 2020
Author: Healthwise Staff
Medical Review:Adam Husney MD - Family Medicine & E. Gregory Thompson MD - Internal Medicine & Kathleen Romito MD - Family Medicine & Arvydas D. Vanagunas MD - Gastroenterology
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