A colonoscopy is an outpatient procedure used to examine the colon, also called the large intestine or bowel. The colon and rectum form the last part of the body’s gastrointestinal (GI) tract. A doctor who specializes in digestive diseases performs a colonoscopy by using a long, narrow, flexible tube to examine the colon. The doctor pays special attention to swollen tissue, ulcers, and polyps (potentially cancerous tissue). The tube (colonoscope) includes a light and a camera, as well as tools that can be used to remove polyps.

Doctors can use a colonoscopy to help diagnose reasons for changes in bowel habits, abdominal pain, bleeding from the rectum, and weight loss. It also is a screening test for colon cancer, allowing them to detect the disease at an early and treatable stage.


The day before the procedure, the patient follows bowel preparation instructions at home, so that little to no stool is present in the intestine for the colonoscopy. This allows for a more complete examination of the intestine. A gastroenterologist performs the colonoscopy at a hospital or outpatient center. Light anesthesia and pain medication relax the patient for the test. Another type of colonoscopy, called virtual colonoscopy, uses CT scans and computer technology to create images of the lining of the colon.

UAB GI program

UAB Medicine is known worldwide as a leading center for digestive and liver disorders. Our gastroenterology and gastrointestinal (GI) program is consistently ranked among the nation’s best by U.S. News & World Report. We see over 20,000 patients and perform more than 12,000 outpatient procedures each year.

Our GI program is also historically significant. The inventor of the endoscope, Basil Hirschowitz, M.D., founded our program more than 50 years ago. His innovation revolutionized diagnoses for GI and other conditions and continues to inspire us today. Our interventional endoscopy group, which includes endoscopic ultrasound, is one of the busiest and most prestigious in the country – both clinically and academically.

UAB Medicine continues to lead advancements in gastroenterology through active clinical research trials involving the latest drug therapies and other treatments for digestive disorders. Our doctors and scientists are searching for causes and cures for many GI illnesses through basic research. For example, they study how the bacteria in our intestines affect our health.

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