Gastroenterology Coding Alert

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

Florida Subscriber Answer: ICD-9 uses the abbreviations NEC and NOS to denote diagnoses -not elsewhere classified- and -not otherwise specified.- NEC is equivalent to using an -other- code selection, and NOS is equivalent to using an -unspecified- code selection.
 
Think of NEC as a lack of specificity in ICD-9. Your gastroenterologist provides specific findings, but ICD-9 does not list a specific code that describes the diagnosis. On the other hand, consider NOS the fault of insufficient documentation, which does not provide enough information to assign a more specific diagnosis code.
 
An example of when you would use an NEC code: Your gastroenterologist specifies -Atony colon disorder.- You look in the 564 category, Functional digestive disorders, not elsewhere classified, for the appropriate code. Codes 564.0-564.7 do not list the manifestation that the physician indicated, so you should report 564.89 (Other functional disorders of intestine), which includes -Atony of colon.-
 
But suppose the gastroenterologist notes simply, -gastric ulcer.- The physician doesn't specify acute or chronic, so you should report 531.9x, which includes -unspecified as acute or chronic, without mention of hemorrhage or perforation.-