In medicine, not otherwise specified (NOS) is a subcategory in systems of disease/disorder classification such as ICD-9, ICD-10, or DSM-IV. It is generally used to note the presence of an illness where the symptoms presented were sufficient to make a general diagnosis, but where a specific diagnosis was not made. The DSM-IV, for example, "applies the term not otherwise specified (NOS) to a disorder or disturbance that does not meet the criteria for the specific disorders already discussed".Patricia G. O'Brien, Winifred Z. Kennedy, M.S.N., R.N., Karen A Ballard, M.A., R.N., Psychiatric Mental Health Nursing (2012), p. 501. The term was introduced because "it is sometimes impossible for the practitioner completing the diagnostic assessment to categorize all the symptoms that a client is experiencing into one diagnostic category".Sophia F. Dziegielewski, DSM-IV-TR in Action (2013), p. 50-51. In the context of mental health diagnoses, four situations have been outlined for which such a diagnosis may be considered appropriate:
It is noted, however, that the use of an NOS classification invites scrutiny when billing or seeking reimbursement for practitioners.
Examples This classification is commonly used in psychiatric diagnoses, such as in: DD-NOS, depressive disorder ED-NOS, eating disorder MD-NOS, mood disorder PD-NOS, personality disorder PDD-NOS, pervasive developmental disorder Psychotic disorder not otherwise specified, psychotic disorder Dissociative disorder not otherwise specified, dissociative disorder It is also used in the conditions: PTCL-NOS, peripheral T-cell lymphoma not otherwise specified Adenocarcinoma not otherwise specified
The ICD-10 also uses this phrase for various things, such as: Fall from, out of or through building, not otherwise specified (W13.9)
The phrase is also used within the List of UN numbers, where it refers to a generic entry, e.g. "UN 1993: Flammable liquid, N.O.S.".
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