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ICD-9 and ICD-10 – What Are Some of the Differences?

Consistent with ICD-9, ICD-10 was developed by the World Health Organization (WHO) and ICD-10-CM represents the Clinical Modification developed through the National Center for Health Statistics (NCHS) under the Centers for Disease Control (CDC) for use in the United States. ICD-10-CM will be maintained by the NCHS and replaces Volume 1 and Volume 2 of ICD-9-CM currently in use for diagnosis coding for all inpatient and outpatient visits.

In contrast, ICD-10-PCS was developed by the Centers for Medicare and Medicaid Services (CMS) within the Department of Health and Human Services (HHS) as an inpatient procedural coding system. The PCS portion of ICD-10 is unique to the United States and will replace the codes in Volume 3 of ICD-9-CM that are currently assigned for inpatient procedures.

Following are some of the specific structural differences between ICD-9-CM and ICD-10-CM:

TABLE 1: Comparison of Diag Code Sets  
3-5 Characters in length 3-7 Characters in length
Approximately 13,000 codes Approximately 68,000 codes
First character may be alpha (V or E) or numeric, characters 2-5 are numeric Character 1 is alpha; Characters 2 and 3 are numeric; characters 4-7 are alpha or numeric
Limited space for adding new codes Flexible for adding new codes
Lacks detail Very specific
Lacks laterality Has laterality (i.e. identifying right vs. left)

With the expansion of the number of characters in the ICD-10-CM diagnosis codes, there is greater specificity identifying disease etiology, anatomic site, and severity.

TABLE 2: ICD-10-CM Code Structure
Characters 1 through 3 – Category
Characters 4 through 6 – Etiology, anatomic site, severity, or other clinical detail
Character 7 – Extension

Following is an example showing the more detail gained through the added characters:

TABLE 3: ICD-10-CM Code Detail
S52                   Fracture of the forearm
S52.3                Fracture of the shaft of the radius
S52.32             Transverse fracture of the shaft of the radius
S52.321           Displaced transverse fracture of the shaft of the right radius
S52.321A         Displaced transverse fracture of the shaft of the right radius,initial encounter
                         for closed fracture

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— Compiled by former CIPROMS ICD-10 Coordinator, Angela Hickman, CPC, CEDC, AHIMA-Approved ICD-10 CM/PCS Trainer, AHIMA Ambassador. All rights reserved. For use or reprint in your blog, website, or publication, please contact us at cipromsmarketing@ciproms.com.


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