Colonoscopy is extremely effective for diagnosing and evaluating a number of gastrointestinal disorders. It is the only endoscopic procedure in which the inner lining of the entire colon can be viewed. Often during the same procedure, the provider can use the colonoscope to take tissue samples, remove polyps, or control bleeding. Additionally, colonoscopy has proven to reduce the number of new cases of colon cancer as well as the number of colon cancer deaths.
Colonoscopy has been found to be extremely safe when performed by a well trained provider such as a gastroenterologist. Although quite rare, most complications are related to sedation, such as heart and breathing problems. Bleeding can occur after polyp removal or from the procedure itself, and may require additional treatment such as hospitalization and/or blood transfusions. Another serious but rare risk is perforation, or partial tearing of the colon, which may require surgery to repair. There is also a slight risk of missed lesions or diagnosis. Even with careful inspection and sampling, disease can be missed.
There are alternative methods to examine the colon, but none are considered more accurate at colon cancer and polyp detection than colonoscopy. These include:
- Flexible sigmoidoscopy, which uses a sigmoidoscope to view the rectum and the lower part of the colon, called the sigmoid colon. This exam does not look at the first, or proximal, parts of the colon, but allows for polyp removal and tissue sampling in the lower part of the colon and rectum.
- CT colonography, or virtual colonoscopy, which uses computed tomography, or CT, technology to create images of the inside of the colon. This only detects polyps that are greater than five millimeters in size, and does not allow for tissue sampling or removal.
- Barium enema, or lower GI series, which uses a series of x-rays and barium inserted into the colon as a contrast agent. This imaging study is not as accurate as CT colongraphy at detecting small polyps, and does not allow for tissue sampling or removal.
- Fecal occult blood testing, or FOBT, which is an analysis of a stool sample. This method does not visualize the colon or allow for tissue sampling or removal.
If any of the above tests suggest the presence of polyps or cancer, a conventional colonoscopy is required to follow up.