Depending on which parts of the bowels, or intestines, are under evaluation, doctors may record images using techniques such as upper endoscopy, colonoscopy and sigmoidoscopy, according to WebMD. Most methods are nonsurgical and rely on inserted devices with attached lighting and cameras to capture footage.
Colonoscopy and sigmoidoscopy are frequently used for finding polyps and screening patients for colorectal cancer, notes the American Cancer Society. Sigmoscopy focuses solely on the rectum and lower colon, or sigmoid colon, so the exam typically lasts only 10 to 20 minutes. A flexible tube measuring 2 feet in length, known as a sigmoidoscope, is slowly inserted into the colon, releasing air to help widen the colon. A built-in camera transmits images to a computer screen. A colonoscopy uses a similar procedure and device, known as a colonoscope, but lasts about 30 minutes because the camera has to travel up the entire colon.
An upper endoscopy is useful for viewing the upper small intestine, according to WebMD. Since the procedure is used for examining the digestive tract as well, the endoscope must be inserted through the mouth. Colonoscopy and standard endoscopy techniques aren't effective for viewing the three main sections of the small intestine, the American Society for Gastrointestinal Endoscopy explains. In these cases, doctors perform a capsule endoscopy by providing a pill-sized camera for patients to swallow. This method allows physicians to check the small intestine for signs of ulcers, inflammation, bleeding and tumors.