Objectives: To evaluate the specificity, sensitivity, and positive predictive value of fecal occult blood testing (FOBT) in symptomatic patients, with colonoscopy as the gold standard, and to assess the usefulness of FOBT as an ancillary examination in symptomatic patients for whom total colonoscopy is indicated.
Methods: We studied 439 consecutive patients who underwent Hemoccult II testing before total colonoscopy.
Results: The sensitivity, specificity, and positive predictive value for colorectal neoplasia (cancer and adenomatous polyps) was 76.5%, 56.7%, and 27.6%, respectively. The sensitivity, specificity, and positive predictive value for colorectal cancer were 69.2%, 73.2%, and 7.3%, respectively.
Conclusions: The sensitivity, specificity, and positive predictive value of FOBT are difficult to estimate from screening programs, because Hemoccult-negative individuals do not undergo examination of the colon, and many of the Hemoccult-positive cases do not undergo total colonoscopy. With total colonoscopy serving as the gold standard, FOBT does not appear to be of much value as an ancillary examination in patients with symptoms potentially attributable to the lower gastrointestinal tract.