Radiology 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 abbreviation NEC for diagnoses “not elsewhere classifiable” and NOS for diagnoses “not otherwise specified.”

NEC: Think of NEC as the code set’s fault. Use an  NEC code when the physician provides specific findings  but the ICD-9 code set does not list a specific code for that diagnosis.

Example: The physician specifies spinal nerve root compression. You look in the 724.x category--“Other and unspecified disorders of back”--for the appropriate code. Codes 724.0-724.8 do not list the manifestation that the physician indicated, so you should report 724.9 (Other unspecified back disorders), which includes “compression of spinal nerve root NEC.”

NOS: Consider NOS the fault of insufficient information. If the documentation doesn’t provide enough information to assign a more specific diagnosis code, choose an NOS code.

Example: Suppose the physician notes “vertebrogenic syndrome.” The physician doesn’t specify what the syndrome is, so you should report 724.5 (Backache, unspecified). This code includes “vertebrogenic (pain) syndrome NOS.”

Best practice: Before reporting an unspecified diagnosis, double-check with the physician to determine whether a more specific diagnosis exists. This may not always be possible if you often code from other physicians’ orders or if the patient needs further diagnostic tests before the physician can determine a specific diagnosis.

Your ICD-9 manual may highlight NEC codes in gray and NOS codes in yellow, but check your specific manual to be sure.