Question: I was looking at the ICD-10-CM manual, and I noticed NEC and NOS. I know they stand for Not Elsewhere Classifiable (NEC) and Not Otherwise Specified (NOS), but how should I use them in ICD-10-CM?
California Subscriber
Answer: Like ICD-9, the NEC (Not Elsewhere Classifiable) abbreviation contains codes for “other” types of specified conditions that haven’t already been classified. When your physician doesn’t clearly specify the condition, you can use a NOS (Not Otherwise Specified) code — although payers usually frown upon this process.