Doing diagnosis: whether and how clinicians use a diagnostic tool of uncertain clinical utility.

Diagnosis is fundamental to the practice of medicine and mastery of it is central to the process of both becoming and practicing as a doctor. We focus on diagnosis as a process, in particular from the perspective of clinicians performing it. We explore how UK clinicians exercise discretion about whether and how to use a diagnostic tool (invasive urodynamic tests - IUT) for which there is, currently, no clear, high-quality evidence. Interviews were conducted with a purposive sample of 18 clinicians who had previously completed a survey on their use of IUT. Analysis was based on the constant comparative method. Participants tended to be polarised in their view of IUT. While many regarded it as a valuable diagnostic tool that they used frequently and thought was important, others reported using it only infrequently, and some were sceptical of its value in the diagnostic process even if they commonly used it. In addition to the anticipated clinical functions (e.g. adding to understanding of the condition, helping determine best treatment) there were additional, more social, functions that IUT could serve, including fitting in with local practice and helping to defend against possible future litigation. We discern two distinct approaches to the practice of diagnosis: one approach means 'leaving no stone unturned' and seeking all available evidence, proven or otherwise; while a second means using clinical judgement to say 'enough is enough' and thereby avoid exposing patients to possibly unnecessary tests and potentially wasting scarce healthcare resources.