Flexible sigmoidoscopy in asymptomatic patients with negative fecal occult blood tests

Although the American Cancer Society and others have established guidelines for colorectal cancer screening, questions of who and how to screen still exist.

A 60-cm flexible sigmoidoscopy was performed on 1000 asymptomatic patients, 45 years of age or older, with negative fecal occult blood tests, who presented for routine physical examinations. Patients with clinically significant lesions were referred for colonoscopy. The proportion of lesions that would not have been found if the 24-cm rigid or the 30-cm flexible sigmoidoscope had been used was identified.

Using the 60-cm flexible sigmoidoscope, lesions were found in 3.6% of the patients. Eighty percent of the significant lesions were beyond the reach of the 24-cm rigid sigmoidoscope and 37% were beyond the reach of the 30-cm sigmoidoscope. Thirty-six patients with lesions were referred for colonoscopy; additional lesions were found in 14%. A total of 62 lesions were discovered, including tubular adenomas, villous adenomas, tubular villous adenomas (23 of the adenomas with atypia), and one adenocarcinoma. The highest percentage of lesions discovered were in the sigmoid colon and the second highest percentage were in the ascending colon.

The 60-cm flexible sigmoidoscope was able to detect more lesions than either the 24-cm or 30-cm sigmoidoscope when used in asymptomatic patients, 45 years of age and over, with negative fecal occult blood tests. When significant lesions are discovered by sigmoidoscopy, colonoscopy should be performed.