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A diagnosis of 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.

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 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.


An example of such a diagnosis is "fever of unknown origin": to explain the cause of elevated temperature the most common causes of unexplained fever (infection, neoplasm, or collagen vascular disease) must be ruled out.

Other examples include:

See alsoEdit


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  3. ^ Freudenreich, O (December 2012). "Differential Diagnosis of Psychotic Symptoms: Medical "Mimics"". Psychiatric Times.
  4. ^ Kwan ES, Wolpert SM, Hedges TR, Laucella M (February 1988). "Tolosa-Hunt syndrome revisited: not necessarily a diagnosis of exclusion". AJR Am J Roentgenol. 150 (2): 413–8. doi:10.2214/ajr.150.2.413. PMID 3257334.
  5. ^ Maltsman-Tseikhin, A; Moricca, P; Niv, D (June 2007). "Burning mouth syndrome: will better understanding yield better management?". Pain Practice. 7 (2): 151–62. doi:10.1111/j.1533-2500.2007.00124.x. PMID 17559486.
  6. ^ Prince, Jim McMorran, Damian Crowther, Stew McMorran, Steve Youngmin, Ian Wacogne, Jon Pleat, Clive. "primary polydipsia - General Practice Notebook". Retrieved 2016-11-22.