Diagnosis of exclusion

A diagnosis of exclusion or by exclusion (per exclusionem) is a diagnosis of a medical condition reached by a process of elimination, which may be necessary if presence cannot be established with complete confidence from history, examination or testing. Such elimination of other reasonable possibilities is a major component in performing a differential diagnosis.

Diagnosis by exclusion tends to occur where scientific knowledge is scarce, specifically where the means to verify a diagnosis by an objective method is absent. As a specific diagnosis cannot be confirmed, a fall back position is to exclude that group of known causes that may cause a similar clinical presentation.

The largest category of diagnosis by exclusion is seen among psychiatric disorders where the presence of physical or organic disease must be excluded as a prerequisite for making a functional diagnosis.

Diagnosis of exclusion is a terribly cost ineffective situation, as costs mount in terms of passage of time to diagnosis, lengthy and complicated diagnostics, commitment by patient, family, and/or caretakers, as well as high burdens on healthcare systems. More precise methods, and development of clear, quick, and resource effective diagnostics is sorely needed to lower the cost of care and productive losses.