What is colonoscopy? 

Gastroenterologists use colonoscopy to screen for colorectal cancer. This minimally invasive endoscopic procedure enables doctors to examine the lining of a patient’s rectum and large intestine (colon) for abnormalities.  

When they perform a colonoscopy, gastroenterologists pass an endoscope or colonoscope (i.e., a thin and flexible tube with a light and camera on the leading end) through a patient’s rectum and into the colon. Doctors then carefully examine the lining of the patient’s colon for polyps or any other abnormalities. If any polyps are detected, they remove them using a small snare that’s attached to the endoscope/colonoscope. Most colorectal cancer can be prevented by removing these polyps.  

In addition to using this procedure to screen people for colorectal cancer, gastroenterologists use colonoscopy to evaluate patients who have colorectal bleeding, abdominal pain and chronic diarrhea. This is known as a diagnostic colonoscopy.  

Gastroenterologists also perform surveillance colonoscopies to examine patients who have had colon polyps removed in the past.