Relative Frequency of Upper Gastrointestinal and Colonic Lesions in Patients with Positive Fecal Occult-Blood Tests

When used to screen large populations, guaiac-based fecal occult-blood tests have been shown to prevent death from colorectal cancer. 1 – 3 Nonetheless, drawbacks associated with their use remain, including a high rate of false positive tests (i.e., a lack of specificity), 4 – 6 which can lead to further testing and expense. 5 , 7 , 8 Bleeding lesions anywhere in the gastrointestinal tract may produce positive results on guaiac-based fecal occult-blood tests. Guaiac-based tests are thought to be unreliable for the detection of occult bleeding from the upper gastrointestinal tract because hemoglobin (or heme), which is the component in blood that causes a positive reaction, . . .