ICD Overview Page 2
	from these reference areas first, then finalize the full diagnosis in the CODES (Volume 1) file last. The ICD codes are grouped into families of codes within 3 digit classifications. All but 146 3 digit classification codes contain a family of four digit subclassification
	codes, many of these contain additional families represented with 5th digit codes. Any code that contains a level of codes beyond it is considered to be a non-specific code and will not be accepted for billing. For example: Code 460-Acute Nasopharyngitis is billable since there are no codes for this family beyond the 3 digit classification Code 493-Asthma has not only fourth digit codes (493.0 Extrinsic Asthma, 493.1 Intrinsic Asthma, etc) but also fifth digit codes (493.00 Extrinsic Asthma with Status Asthmaticus, and etc) We have chosen to use the concept of driving a car so that you can 'go until you reach the most specific code.' Once you reach the 3 digit classification codes, each code number is listed with either a green light or a red light. Green lights represent an intersection you must pass through on you way to more codes that must be reviewed in order to successfully bill. Red light codes represent codes that are at the end of the 'drive' and have no additional code intersections beyond them. CMS produces the ICD-9-CM Guidelines for Coding and Reporting that goes into significant detail on coding from the alpha index, tables, and Volume 1 chapters. You can download a copy of that here.