Accuracy and value of the Hemoccult test in symptomatic patients.

Hemoccult faecal occult blood testing is widely advocated as a screening test for colorectal cancer but few studies have shown its correlation with conventional methods of investigation for colorectal disease. In a prospective study of 802 symptomatic patients with suspected colorectal disease there was good patient compliance (92.5%) and a high specificity for colorectal cancer (85.4%). The false positive rate was 8.6% (12 of 140 patients with positive results), and while the test result was positive in 22 of 26 colonic cancers the false negative rate for rectal cancer (45.4%) should not detract from its value as a screening test if proper digital anorectal and proctosigmoidoscopic examination are widely practised. A positive Hemoccult test result is a useful indicator for the need to proceed to full colorectal investigation, including colonoscopy.