ICD-10 codes differ from ICD-9 codes in their basic form and structure, which is good news for anyone who needs to be able to differentiate between the two without being familiar with individual codes.  ICD-10 codes tend to be longer than ICD-9 codes and to have more flexibility as to whether characters can be numbers or letters.  See below for additional details.

ICD-9 diagnosis codes have 3-5 characters. The characters are all numbers, except for supplementary codes – V and E codes.

ICD-10 diagnosis codes have 3-7 characters.  The first character is always a letter, and the rest can be letters or numbers.

ICD-9 Example

 

ICD-10 Example