Limitations of combined flexible sigmoidoscopy and double contrast barium enema in patients with rectal bleeding.

Eighty-seven outpatients with non-massive rectal bleeding or asymptomatic positive fecal occult blood were evaluated with 35 cm flexible sigmoidoscopy, double contrast barium enema (DBCE) and colonoscopy. 82% had hemorrhoids and 35% harbored colorectal neoplasia. The combination of flexible sigmoidoscopy and DCBE missed none of 7 malignant lesions. However, 36% of benign polyps greater than or equal to 1 cm and 60.25% of those less than 1 cm were not detected by this combination. The presence of hemorrhoids should not prevent a search for colon neoplasia and colonoscopy is the preferred method.