Primary Care Coding Alert

Question: What do "NEC" and "NOS" mean in ICD-9 coding? How should I choose between them?

Florida Subscriber
 
Answer: ICD-9 uses the abbreviations NEC and NOS for "not elsewhere classified" and "not otherwise specified." Think of NEC as the book's fault. Your internist provides specific findings, but the book does not list a specific code that describes the diagnosis. On the other hand, consider NOS your physician's fault. Your internist's documentation does not provide enough information to assign a more specific diagnosis code. NEC codes are frequently highlighted in gray in the ICD-9 manual, and NOS codes are usually highlighted in yellow.
  
An example of when you would use an NEC code: Your physician specifies diabetic hypertension. You look in the 250.xx category, diabetes mellitus, for the appropriate code. Codes 250.0-250.7 do not list the manifestation that the physician indicated. Since the doctor stated a manifestation, you can't use 250.9x (Diabetes with unspecified complication), so in this case the correct ICD-9 code is 250.80 (Diabetes with other specified manifestations; type II or unspecified type ...).  
  
In contrast, suppose the internist notes "complicated type II, uncontrolled diabetes." The physician doesn't specify what the complication is, so you should report 250.92 (Diabetes with unspecified complication). The fifth-digit subclassification "2" indicates that the diabetes is type II, uncontrolled, as specified by ICD-9.