ICD-10-CM Abbreviations: NEC, NOS

by  Christine Woolstenhulme, QMC QCC CMCS CPC CMRS
May 6th, 2015 - Reviewed/Updated Aug 8th

The difference between NEC and NOS is very specific and not to be confused as they are two very different abbreviations.

NEC - When a specific code is not available for a condition, the Index directs the coder to the “other specified” code in the Tabular List.  NEC is used to indicate the diagnosis is specific; however, the coding system is not specific enough. 

 Example: Alphabetical Index

Cataract

Specified NEC H26.8 Tabular List

H26.8 - Other specified cataract

NOS “Not otherwise specified” This abbreviation is the equivalent of unspecified, indicating the documentation does not provide enough information to assign a more specific code.

Example:  Tabular List

I50.9 - Heart failure, unspecified

Biventricular (heart) failure NOS

Cardiac, heart or myocardial failure NOS

Congestive heart disease

Congestive heart failure NOS

Right ventricular failure

(secondary to left heart failure)

ICD-10 Guidelines: Abbreviations

 a. Alphabetic Index abbreviations

NEC “Not elsewhere classifiable” This abbreviation n the Alphabetic Index represents “other specified”. When a specific code is not available or a condition the Alphabetic Index directs the coder to the “other specified” code in the Tabular List

NOS “Not otherwise specified “This abbreviation is the equivalent of unspecified.

b. Tabular List abbreviations

NEC “Not elsewhere classifiable” This abbreviation in the Tabular List represents “other specified”. When a specific code is not available for a condition the Tabular List includes an NEC entry under a code to identify he code as the “other specified” code.

NOS “Not otherwise specified” This abbreviation is the equivalent of unspecified.