Colonoscopy is a procedure that uses a long, flexible, narrow tube with a light and tiny camera on one end, called a colonoscope or scope, to look inside the rectum and entire colon. Colonoscopy can show irritated and swollen tissue, ulcers, and polyps—extra pieces of tissue that grow on the lining of the intestine.
Why is a colonoscopy performed?
A colonoscopy is performed to help diagnose:
- changes in bowel habits
- abdominal pain
- bleeding from the anus
- weight loss
A gastroenterologist also performs a colonoscopy as a screening test for colon cancer. Screening is testing for diseases when people have no symptoms. Screening may find diseases at an early stage, when a health care provider has a better chance of curing the disease.
How is a colonoscopy performed?
A gastroenterologist performs a colonoscopy at a hospital or an outpatient center. In most cases, light anesthesia and pain medication help people relax for the test. The medical staff will monitor people’s vital signs and try to make people as comfortable as possible. A nurse or technician places an intravenous (IV) needle in a vein in the arm to give anesthesia.
For the test, the person will lie on a table while the gastroenterologist inserts a colonoscope into the anus and slowly guides it through the rectum and into the colon. The scope inflates the large intestine with air to give the gastroenterologist a better view. The camera sends a video image of the intestinal lining to a computer screen, allowing the gastroenterologist to carefully examine the intestinal tissues. The gastroenterologist may move the person several times so the scope can be adjusted for better viewing. Once the scope has reached the opening to the small intestine, the gastroenterologist slowly withdraws it and examines the lining of the large intestine again.
For the test, the person will lie on a table while the gastroenterologist inserts a colonoscope into the anus and slowly guides it through the rectum and into the colon.
The gastroenterologist can remove polyps during colonoscopy and send them to a lab for testing. Polyps are common in adults and are usually harmless. However, most colon cancer begins as a polyp, so removing polyps early is an effective way to prevent cancer.
The gastroenterologist may also perform a biopsy, a procedure that involves taking a small piece of intestinal lining for examination with a microscope. The person will not feel the biopsy. A pathologist—a doctor who specializes in diagnosing diseases—will examine the tissue.
The gastroenterologist may pass tiny tools through the scope to remove polyps and take a sample for biopsy. If bleeding occurs, the gastroenterologist can usually stop it with an electrical probe or special medications passed through the scope. Colonoscopy usually takes 30 to 60 minutes.
After the Colonoscopy
- People may need to stay at the hospital or outpatient center for 1 to 2 hours after the procedure.
- Cramping or bloating may occur during the first hour after the test.
- The anesthesia takes time to completely wear off.
- Full recovery is expected by the next day, and people should be able to go back to their normal diet.
- A member of the health care team will review the discharge instructions with the person—or with an accompanying friend or family member if the person is still groggy—and provide a written copy. The person should follow all instructions given.
- A friend or family member will need to drive the person home after the procedure.
- If the gastroenterologist removed polyps or performed a biopsy, light bleeding from the anus is normal.