With the implementation of ICD 10 in 2015, we are now going to use these codes in future. Since, we were using ICD-9 CM codes for long time we always like to compare with ICD-10 codes. There are not many changes as long as the guidelines are considered. Yes, with the number of codes and use of alphanumeric codes, there is certainly a major difference between ICD-9 and ICD-10 diagnosis codes. So, we will checkout the basic differences between these two versions of diagnosis codes. Checkout my previous post on coding ICD 10 for unilateral and bilateral diagnosis codes to learn more about new codes.

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Basic about ICD-9 CM diagnosis codes

If we put is short, they are only 3-5 digits codes. Only E or V alphabets used in ICD-9 alphanumeric codes. Only first digit was used for alphabet if required, otherwise all other digits from 2-5 are numeric. The decimal was used only after the third digit or character.
Examples: 486– Pneumonia
786.50– Chest Pain, Unspecified
V22.2– Pregnancy state Incidental

Basics about ICD-10 Diagnosis Codes

The new diagnosis codes will be 3-7 digits long. The 1st digit will be alpha, 2nd digit will be numeric and 3-7 digit will be either alpha or numeric. Here also, the decimal is used after 3 rd character.
Example: A78 – Q fever
A69.21 – Meningitis due to Lyme disease
S52.131A – Displaced fracture of neck of right radius, initial encounter for closed fracture.

The first three character denotes the CATEGORY
Example M84 disorder of continuity of bone
4,5 and 6 character (if applicable) denotes the etiology, anatomic and severity.
An Extension character is used for 7th digit.
Example:
M84.311A: stress fracture, right shoulder; initial

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New feature in ICD-10 CM

A Placeholder X character is used at few codes to allow future expansion. When the placeholder exists, the X must be used in order to consider the code as valid code. An example of this is at the poisoning, adverse effect and under dosing codes, categories T36-T50.
Example:

H40.11X1     Mild stage primary open-angle glaucoma

Applicable 7th character in ICD-10

 When there is an applicable seventh character, it should be always on the 7th digit. The applicable 7th character is always required for all codes within some category. If there is no character in before 7th digit then we can go ahead and use placeholder X to fill the gap and use applicable 7th character on 7th digit.
Example:T79.0XXA    Initial encounter for a traumatic air embolism.