Years ago my internist said that I should have a flexible sigmoidoscopy every three years by him. Now he tells me that I should see a gastroenterologist for a colonoscopy. Why the different advice?

In the 1960's, before colonoscopy was found to be feasible, the only diagnostic modalities which were available for detecting colorectal pathology were the barium enema and the rigid ten inch proctoscope. These tools were rudimentary and inaccurate, and as a result, much of the pathology in the colon went undiagnosed. Medical textbooks and journals of the time stated that 2/3 of colon polyps and cancers were found in the last two feet of colon closest to the rectum. When colonoscopy first became a reality in the early 1970's, the Office of the Surgeon General announced that the best colon cancer detection and control program for this country would have every family physician and internist perform rigid or flexible sigmoidoscopy; patients would be referred to gastroenterologists for total colonoscopy only if a polyp was found on in the last two feet of the colon during sigmoidoscopy. As more gastroenterologists became trained and proficient in colonoscopic technique in the 1970's and 1980's, more colonoscopies were performed each year. The more widespread use of colonoscopy led to the discovery that there were more polyps and cancers further up in the colon than the area served by the flexible sigmoidoscope. Furthermore, by the 1990's, statistics showed that the colonoscopic removal of adenomatous polyps of the colon reduced the expected rate of colon cancer formation in this country.

When US public health officials realized that there were more polyps and cancers 3, 4, and 5 feet into the colon than previously expected and that colonoscopic removal of polyps could reduce the number of colon cancers that developed, colonoscopy became the recommended procedure for colon cancer screening and surveillance; this was only logical since it was apparent that the entire colon was at risk for polyp and cancer development. In response to the recommendation that colonoscopy be the procedure of choice, the Health Care Financing Administration (the 1980's name of the agency which operates Medicare) in the late 1980's cut the professional fees paid to doctors for performing colonoscopy to an amount which was less than the amount Medicare previously paid for flexible sigmoidoscopy. The logical paradigm shifted, colonoscopy became the more prevalent procedure, and family physicians were taught that they should refer patients to gastroenterologists at the outset for colonoscopy and that they should not fool around with the flexible sigmoidoscope any more.