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Comparison of ICD-9 and ICD-10

Enhancements from ICD-9 to ICD-10
  1. ICD-10 will allow greater detail and granularity to define more clearly the patient's medical condition(s). ICD-9 has roughly 15,000 codes whereas ICD-10 has approximately 68,000.
  2. ICD-9 is 30 years old. It has outdated terms, limited capability to create new codes, and has inconsistencies related to current medical practices. ICD-10 is built to allow for flexibility in the growth and changes to codes and medical terminology due to its level of clinical detail.

Diagnosis Codes


  1. ICD-9 is 3 to 5 digits in length and can start with a number, E, or V (not counting the dot). Except for codes beginning with E, a dot may go after the third character if the code has more than three characters.
  2. For ICD-9 “E” codes, the dot may go after the fourth character if the code has more than four characters.

ICD9 Table


  1. Diagnosis coding under ICD-10 uses 3 to 7 digits and start with a letter, not counting the dot. A dot can go after the third character if the code has more than three characters.       
    ICD10 Table
  2. An example of the conversion would be 733.6 (Tietze’s Syndrome) in ICD-9 would be M94.0 in ICD-10.
  3. While only one ICD-9 code may exist for a condition, it does not always mean there will be a one-to-one mapping to ICD-10. An example of this is 649.51 (spotting complications during pregnancy). In ICD-10, this breaks out to O26.851, O26.852, and O26.853, depending on when the condition develops during a particular trimester.

Procedure Codes


  1. ICD-9 procedure codes start with a digit and are two to four characters long. A dot may go after the second digit if the code has more than two digits. An example is 39.50, angioplasty.


  1. ICD-10 procedure codes are always seven characters long and allow no dot. An example is 0DN90ZZ release of duodenum, open approach.
  2. ICD-10 will not replace the Current Procedural Terminology (CPT) and Healthcare Common Procedure Coding System (HCPCS) code sets for reporting services and procedures in outpatient and office settings.
  3. The alpha characters in ICD-10 are not case sensitive. The letters O and I are not used to avoid confusion with the numbers 0 and 1.
  4. The additional characters in the ICD-10 procedure code set allows for identifying the body system, root operation, body part, approach, and device involved in the procedure. The code structure in the Medical and Surgical section looks like this.
 Character  1
 2  3  4  5  6  7
 Definition  Name of Section  Body System
 Root Operation
 Body Part
 Approach Device

If you have any questions, please email us at icd-10@iehp.org.