Evaluation of a sequence of diagnostic tests using the workup of ureteral stone as a model.

Additional tests are not always beneficial and can increase costs significantly while increasing the group of patients with an equivocal diagnosis. In general, diagnostic testing should cease for a group of patients when the tests that have been performed result in a sufficiently high level of diagnostic certainty and also result in the largest group of true positive or true negative diagnoses. Evaluation of diagnostic tests must include consideration of the results of sequences of tests, equivocal results of tests, and the effect of added costs on both advantageous sequences of tests and total expenditures. Evaluation of the diagnostic tests performed for ureteral stone in the emergency ward demonstrates that a significant group of patients, on whom an intravenous urogram could be avoided can be selected. As an alternative to the IVU in this selected group, hydration and diuresis could be considered. The IVU could be reserved for those patients who did not experience classic relief of pain and passage of stone.