Pediatric Coding Alert

Question: What do "NEC" and "NOS" mean in ICD9 coding? How should I select between them?

Florida Subscriber

Answer: ICD-9 uses the abbreviations NEC and NOS for "not elsewhere classified" and "not otherwise specified," respectively. Think of NEC as the book's fault: Your pediatrician provides specific findings, but the book doesn't list a specific code that describes the diagnosis. On the other hand, consider NOS the equivalent of your doctor's fault: Your pediatrician's documentation doesn't provide enough information to assign a more specific diagnosis code. NEC codes are highlighted in gray in the ICD-9 manual, and NOS codes are highlighted in yellow.
 
For example, you would use an NEC code if your pediatrician 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 pediatrician lists the child took. Because the pediatrician 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 pediatrician notes dermatitis due to ingested substance. The pediatrician didn't specify what the substance was, so you should report 693.8.