Preoperative testing for fecal occult blood: a questionable practice

The benefit of fecal occult blood testing (FOBT) in patients without gastrointestinal symptoms who are hospitalized for an elective surgical procedure is uncertain. To resolve this issue, we analyzed the costs and benefits of preoperative FOBT by the model of a decision tree. In 2- and 3-way sensitivity analyses, the costs of diagnostic and therapeutic procedures and the probabilities of their various outcomes are varied simultaneously so that we might study their joint influence on the outcome of the decision analysis. The decision analysis shows that preoperative FOBT is associated with a smaller benefit than would be its omission. The higher cost and lower net benefit of preoperative FOBT reflect the impact of false-positive tests for occult blood. False-positive FOBT leads to expenditures for negative gastrointestinal work-ups, increased procedural costs, and a diminished rate of success for the elective surgical procedure, by delaying it. This outcome of the analysis is insensitive to large variations in the costs and probabilities built into the model. We conclude that screening for fecal occult blood provides no benefit if done routinely in patients who are hospitalized for any major surgical procedure.