NEC, NOS: There Are Differences
Published on Tue Sep 23, 2003
Question: What do ""NEC"" and ""NOS"" mean in ICD-9 coding? How should I choose between them? Florida Subscriber Answer: ICD-9 uses the abbreviations NEC and NOS to denote diagnoses ""not elsewhere classified"" and ""not otherwise specified."" NEC is the equivalent to using an ""other"" code selection and NOS is the equivalent to using an ""unspecified"" code selection. Think of NEC as the code set's fault: The physician provides specific findings but the ICD-9-CM code set does not list a specific code that describes the diagnosis. On the other hand consider NOS the physician's fault: The documentation does not provide enough information to assign a more specific diagnosis code. NEC codes are frequently highlighted in gray in the ICD-9 manual and NOS codes are usually highlighted in yellow. An example of when you would use an NEC code: The physician specifies spinal nerve root compression. You look in the 724.x category - ""Other and unspecified disorders of back"" - for the appropriate code. Codes 724.0-724.8 do not list the manifestation that the physician indicated so you should report 724.9 (Other unspecified back disorders) which includes ""compression of spinal nerve root NEC.""
In contrast suppose the physician notes ""vertebrogenic syndrome."" The physician doesn't specify what the syndrome is so you should report 724.5 (Backache unspecified). This code includes ""vertebrogenic (pain) syndrome NOS."" Ideally before reporting an unspecified diagnosis you should double-check with the physician to determine whether a more specific diagnosis exists. However because radiology coders often code from other physicians' orders this may not be possible in all situations. "
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