How do we define the term idiopathic?

Purpose of reviewThe term idiopathic is often used to describe a disease with no identifiable cause. It may be a diagnosis of exclusion; however, what specific minimum investigations need to be performed to define idiopathic is not always clear. This commentary describes the problems inherent in reaching a definition for the term idiopathic.Recent findingsThere is limited literature describing methodology to define a condition with no clear diagnostic criteria. This article offers chronic pelvic pain (CPP) syndrome as an example, in which structured qualitative interviews, literature searches and group consensus discussions were undertaken to produce a working definition for idiopathic CPP.SummaryIt is important to correctly develop these standardized definitions for use as outcome measures in research and as clinical indicators in healthcare.