ICD-10-CM diagnosis codes

The difference between NOS and NEC codes

Not Otherwise Specified (NOS) and Not Elsewhere Classifiable (NEC) codes are similar, so it’s easy to confuse them. It all comes down to what you document in the patient’s medical record for the encounter. Capturing specific information in the record supports codes of higher specificity.

NEC codes are still more specific than NOS codes. Whenever you cannot locate a code to describe a specific condition, use an NEC code ending in “8” instead of an NOS code ending in “9.” Insurance companies will expect that your documentation is specific, even if the code itself cannot be.

Think about a patient who has come to you with a bad case of acne. In the medical record, you wrote only “acne,” not specifying the type. Because there isn’t enough information in the medical record to choose a more precise code, you would choose the code ending with a “9,” or L70.9 acne, unspecified. This is an NOS code.

Now consider a patient who has a problem on her fingernails. The L60 code series (nail disorders) includes codes for ingrown nails, onycholysis, onychogryphosis, nail dystrophy, Beau lines, and yellow nail syndrome. But if your patient has another problem with her nails, you will need to use the code ending in “8” (L60.8, other nail disorders). You have documented a specific condition, but no existing code names the specific condition. This is an NEC code.

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