What should edical codes that contain the descriptive abbreviation NOS be used?

Codes that contain the descriptive abbreviation NOS (Not Otherwise Specified) are used when a more specific diagnosis cannot or has not been made but the symptoms of a condition are present. NOS is used when a code cannot be assigned with the normal level of specificity based on the documentation but the provider chooses not to query or the query process did not result in a more definitive code.