ICD-10-CM Diagnosis Structure

ICD-9 CM   ICD-10 CM  
Three to five characters in length  Three to seven alphanumeric characters 
First digit is numeric but can be alpha (E or V)   First character always alpha. All letters used except U 
Second, third, fourth & fifth digits are numeric  Character number 2 is always numeric. Characters #3 - #7 can be alpha or numeric 
Decimal placed after the first three characters (or with E codes, placed after first four characters)   Decimal placed after the first three characters 
Alpha characters are not case sensitive  Alpha characters are not case sensitive 
Approximately 14,567  Approximately 69,832 
Limited space for adding codes (Minimal)  Flexible (Extensive)  
Laterality is lacking   Laterality provides specificity  
Specificity is limited   Specificity is extensive  
United States Most countries  
17 Chapters  21 Chapters 
V and E codes are in supplemental classifications  V and E supplemental classifications are incorporated into the main classification 
Included in the Nervous System   Disease of Eyes and Ears are in their individual chapters 
Classifies injuries by type   Groups injuries first by specific site (head, arm, leg, and such) and then by type of injury (fracture, open would, and the like)  
  Postoperative complications have been moved to procedure-specific body system chapters  
Gout has been reclassified from the endocrine chapter in ICD-9-CM to the Musculoskeletal chapter in ICD-10-CM  Certain diseases have been reclassified (or reassigned) to a more appropriate chapter to reflect current medical knowledge  
Refers back to fourth and fifth digits Includes full code titles for all codes  
  Addition of a sixth character in some chapters 
  Addition of code extensions (seventh character) for obstetrics, injuries and external causes of injury (Addition of placeholder – X)