Fecal Occult Blood Testing
Sigmoidoscopy

Note: Separate PDQ summaries on Prevention of Colorectal Cancer; Colon Cancer Treatment; and Rectal Cancer Treatment are also available.

Guaiac-based fecal occult blood testing either annually or biennially using rehydrated or nonrehydrated stool specimens in people age 50 to 80 decreases mortality from colorectal cancer. (Level of evidence: 1) Potential harms include false-positive and false-negative results. Colonoscopy, often used to follow up a positive fecal occult blood test, is associated with uncommon but serious complications, including: colonic perforation resulting in sepsis, need for surgical repair procedures, or death. Hemorrhage resulting from colonoscopic polypectomy may require blood transfusion, hospitalization, or surgical intervention.

Level of Evidence

1: Evidence obtained from randomized controlled trials.

Regular screening by sigmoidoscopy in people over the age of 50 may decrease mortality from colorectal cancer. There is insufficient evidence to determine the optimal interval for such screening.

Levels of Evidence

3: Evidence obtained from cohort or case-control studies.

4: Evidence obtained from ecologic and descriptive studies (e.g., international patterns studies, time series).

5: Opinions of respected authorities based on clinical experience, descriptive studies, or reports of expert committees.

Back to Top

Next Section >