Part B Insider (Multispecialty) Coding Alert

Your Medicare payments could be at stake if you don't report the right ICD-9 code.

Are you interchanging the terms "NEC" and "NOS" when coding your diagnoses? This habit could lead you to trouble -- and may result in costly denials if you substitute one for the other.

ICD-9 uses the abbreviations NEC and NOS to denote diagnoses "not elsewhere classified" and "not otherwise specified," respectively.

But although the terms sound similar, they have distinct differences.

"The only way to really understand it is to look at NOS as the equivalent of 'unspecified' and NEC as 'not elsewhere classifiable,' meaning you won't find the term in the ICD-9 book anywhere else," says Terry Fletcher, BS, CPC, CCS-P, CCS, CMSCS, CCC, CEMC, CMC, the CEO of Terry Fletcher Consulting, Inc.

Tip: Think of NOS as a documentation problem: The physician's documentation does not provide enough information to assign a morespecific code.

In black and white: "Codes (usually a code with a 4th digit 9 or 5th digit 0 for diagnosis codes) titled 'unspecified' are for use when the information in the medical record is insufficient to assign a more specific code," according to the ICD-9-CM Official Guidelines for Coding and Reporting.

On the other hand, consider NEC as a shortcoming in the ICD-9 manual: Your doctor provides specific findings, but ICD-9 does not list a specific code that describes them.

In black and white: "Index entries with NEC in the line designate 'other' codes in the tabular," The ICD-9-CM Official Guidelines for Coding and Reporting notes. "These index entries represent specific disease entities for which no specific code."

You might use an NEC code if your physician specifies dermatitis due to herbal supplement. You should look in the 693 category (Dermatitis due to substances taken internally) for the appropriate code.

Codes 693.0-693.9 don't list the substance that the doctor documents that the patient took. Because the doctor states the substance, you shouldn't use the NOS code 693.9 (... due to unspecified substances taken internally). Since ICD-9 doesn't list the identified substance, the correct ICD-9 code is NEC 693.8 (... due to other specified substances taken internally).

In contrast, suppose the physician notes dermatitis due to ingested substance. The doctor didn't specify what the substance was, so you should report 693.9.