ICD-10-CM (International Classification of Diseases, Tenth Revision, Clinical Modification)

Contributor(s): Alex DelVecchio

The International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) is a system used by physicians and other healthcare providers to classify and code all diagnoses, symptoms and procedures recorded in conjunction with hospital care in the United States.

Like its predecessor ICD-9-CM, ICD-10-CM is based upon the International Classification of Diseases, which is published by the World Health Organization (WHO) and which uses unique alphanumeric codes to identify known diseases and other health problems. According to WHO, physicians, coders, health information managers, nurses and other healthcare professionals also use ICD-10-CM to assist them in the storage and retrieval of diagnostic information. ICD records are also used in the compilation of national mortality and morbidity statistics.

The ICD-10-CM revision includes more than 68,000 diagnostic codes, compared to 13,000 in ICD-9-CM. In addition, ICD-10-CM codes include twice as many categories. ICD-10-CM diagnosis codes consist of three to seven digits, compared to the three to five digit system of ICD-9-CM. The increase in the amount and length of ICD-10-CM codes will allow for greater coding specificity.

Despite not being used in American hospitals, the ICD-10-CM code set has been revised yearly since 2003 to keep up with alterations made to ICD-10 by WHO. In preparation for ICD-10-CM implementation, a partial code freeze stopped the regular annual updates to ICD-10-CM codes in October 2011. Since then, there have been limited yearly changes made to the ICD-10-CM coding set with the normal updates scheduled to resume in 2016.

All Health Insurance Portability and Accountability Act-covered entities must begin using ICD-10-CM codes by Oct. 1, 2015, as mandated by the U.S Department of Health and Human Services. The ICD-10-CM implementation deadline has been delayed several times. ICD-10-CM guidelines were initially set to replace ICD-9-CM on Oct. 1, 2013. Two separate year-long extensions to the ICD-10-CM implementation date pushed it back to 2015.

The structure of ICD-10-CM codes is as follows. The first character must be an alpha character, excluding "u." The second and third characters are numeric and characters four through seven can be a combination of numeric and alpha characters. The first three characters categorize the injury and the fourth through sixth characters describe in greater detail the cause, anatomical location and severity of an injury or illness. The seventh character is an extension digit and used to classify an initial, subsequent or sequela (late effect) treatment encounter.

This was last updated in June 2015

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For how long should ICD-10-CM be the coding standard used in the U.S.?
Is it necessary for WHO to change the ICD every year? I think every 5 years will be fine, given the efforts needed to complete it.


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