GI Los Angeles | Gastroenterology Institute of Southern California | Press Releases : A common state-of-the-art digestive health exam Dr. Berookim’s institute provides is the colonoscopy. In a colonoscopy, Dr. Berookim tests the inside of the colon (also known as the large intestine or large bowel) with a colonoscope, which is a four-foot flexible tube the thickness of a finger with a camera and light at its tip. A colonoscopy sounds nerve-wracking; but it’s considered the “gold standard” for colorectal cancer screening . It actually prevents colon cancer, since it is both a diagnostic and therapeutic procedure. A colonoscopy most often looks for the cause of blood in the stool, abdominal pain, diarrhea, a change in bowel habits or other digestive system abnormalities . It is recommended that even healthy people, who are at normal risk for colon cancer, should have their first colonoscopy at age 50 and again every 10 years.