“Other” vs “Unspecified,” NEC vs NOS: Which Residual Code Fits the Record

Section I.A.6 defines the abbreviations, and both definitions are the same in the Index and the Tabular:

“NEC ‘Not elsewhere classifiable’ — This abbreviation in the Alphabetic Index represents ‘other specified.’ When a specific code is not available for 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.”

Section I.A.9 says when each code type is used:

“Codes titled ‘other’ or ‘other specified’ are for use when the information in the medical record provides detail for which a specific code does not exist. Alphabetic Index entries with NEC in the line designate ‘other’ codes in the Tabular List. These Alphabetic Index entries represent specific disease entities for which no specific code exists, so the term is included within an ‘other’ code.”

“Codes titled ‘unspecified’ are for use when the information in the medical record is insufficient to assign a more specific code. For those categories for which an unspecified code is not provided, the ‘other specified’ code may represent both other and unspecified.”

So the two are not degrees of the same thing. “Other” is chosen because the record is too specific for the classification — it names something that has no code of its own. “Unspecified” is chosen because the record is not specific enough. The same category usually carries both: J45.998, Other asthma, and J45.909, Unspecified asthma, uncomplicated, whose inclusion term is “Asthma NOS.”

NOS appears as an inclusion term under the code that takes the undetailed form of a condition — that is the tabular saying “this is the default when nothing more is documented.” T36.0X1, Poisoning by penicillins, accidental, carries the inclusion term “Poisoning by penicillins NOS,” which is the tabular form of the poisoning guideline’s rule that unknown intent defaults to accidental.

Section I.B.18 is the guard against treating unspecified as a failure: “Unspecified codes should be reported when they are the codes that most accurately reflect what is known about the patient’s condition at the time of that particular encounter. It would be inappropriate to select a specific code that is not supported by the medical record documentation or conduct medically unnecessary diagnostic testing in order to determine a more specific code.” The symptom guide linked below covers the same section for signs and symptoms.

1. Look up the documented term in the Alphabetic Index; an NEC entry points to the “other specified” code.
2. Verify in the Tabular: if a specific code exists for the documented form, use it.
3. If the record is specific but no code exists, use the “other” / “other specified” code.
4. If the record does not state the form, use the “unspecified” code — or the “other specified” code where the category has no unspecified code.
5. Do not seek more specificity through unnecessary testing (I.B.18).

1. “Asthma,” no further detail. J45.909 — the inclusion term “Asthma NOS” lives there.
2. A specific asthma variant documented that has no J45 code of its own. J45.998, Other asthma.
3. A penicillin poisoning with no intent documented. T36.0X1-: the inclusion term “Poisoning by penicillins NOS” marks it as the default.

• Choosing an “other specified” code for a record that simply lacks detail — that is the unspecified code.
• Choosing an unspecified code when the record names a specific form with its own code.
• Treating an unspecified code as an error in itself.

• Whether the record names a specific form of the condition.
• Whether that form has its own code — the Index and Tabular decide.
• Whether the category provides an unspecified code at all.