Level 2: Mid-level evidence
About 10% of patients with new rectal bleeding have colorectal neoplasia, based on a prospective study of 265 patients older than 45 years who reported new rectal bleeding at a rural general practice in the United Kingdom over 10.25 years (BMJ. 2006;333:69-70). Patients were evaluated with rigid sigmoidoscopy plus barium enema, flexible sigmoidoscopy, or colonoscopy. Most of the patients were evaluated with rigid sigmoidosocopy plus barium enema. Fifteen patients (5.7%) had colorectal cancer and 13 patients (4.9%) had colorectal adenoma.