ICD-10 was endorsed by the Forty-third World Health Assembly (held in Geneva from 7 – 18 May 1990) and came into use in WHO Member States as from 1994. ICD-10 is the latest classification in the series which has its origins in the 1850s.

Adoption of ICD-10 has been slow in the United States. Since 1988, the USA had required ICD-9-CM codes for Medicare and Medicaid claims, and most of the rest of the American Healthcare Industry followed suit. On 1 January 1999 the ICD-10 (without clinical extensions) was adopted for reporting mortality, but ICD-9-CM was still used for morbidity.

NCHS a division of US Centers for Disease Control & Prevention received permission from the WHO to create a clinical modification of the ICD-10.

The United States Government has assigned the National Center for Health Statistics (NCHS) the responsibility for the development of ICD-10-CM.

The ICD-10-CM will be used for diagnosis coding, and will replace Volumes 1 and 2 of ICD-9-CM.

On January 16, 2009 DHHS published a final rule adopting ICD-10-CM (and ICD-10-PCS) to replace ICD-9-CM in HIPAA transactions, effective implementation date of October 1, 2013. Until that time the codes in ICD-10-CM are not valid for any purpose or use.

CMS announced a further delay of ICD-10 implementation on April 9th 2012 for one more year. The April 9 proposed rule from the Dept. of Health and Human Services for the Implementation of ICD-10-CM and ICD-10-PCS mandates the providers to shift to the new code sets by Oct. 1, 2014.

ICD-10-CM Volumes

The draft version of the year 2012 of ICD-10-CM consists of two volumes.

  • The Tabular List – A list of alphanumeric codes organized by organ systems, etiology, external causes, or other criteria such as symptoms & Signs. Coding conventions & instructions are listed in the tabular list. The list is arranged in the 21 chapters.
  • The Alphabetic Index – An alphabetic index to the conditions in the Tabular List.

Alphabetic Index

The Alphabetic Index for ICD-10-CM includes or will include the following:

  • An index to diseases and conditions coded to Chapters 1 to 19 and Chapter 21.
  • A table of Neoplasms arranged alphabetically by anatomic site with codes for malignant, benign, in situ, uncertain behavior, or unspecified behavior neoplasms.
  • A table of Drugs & Chemicals, used to code poisonings and adverse effects of drugs classified in chapter 19, "Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88)," and Chapter 20.
  • An index to the terms related to the external causes of morbidity and terms in the chapter 20, "External Causes of Morbidity (V01-Y99)".

The Alphabetic Index is organized by main terms that are bold and flush left. Main terms are usually conditions rather than anatomic sites. Main terms for Chapter 21, "Factors Influencing Health Status and Contact with Health Services," include admission (for), aftercare, boarder, convalescence, examination, history, prescription, problem, state of, status, vacation etc.

Main term entries include subterms (also called essential modifiers) that are indented under them main term. Subterm modifiers are indented under the applicable subterm.

See; See also and the abbreviation NEC are alphabetic index coding conventions.

See; See also–cross reference conventions direct the coder to another main term, or to another category or code.

NEC–indicates that the code applies when a more specific code is not available.

Tabular List

The tabular list of ICD-10-CM has the following features:

  • 21 Chapters without any supplementary classification
  • Over all 69,833 codes
  • All codes are alphanumeric with every code begins with an alphabet
  • A code may have three to seven characters with a decimal after first three character
  • Fourth digit may be a letter or number
  • The seventh character extension classifies the encounter types (initial, subsequent,sequela etc.)
  • For codes with less than 6 characters that require a 7th character, a placeholder X should be assignedin between to complete the code with 7 characters. The 7th character must always be on the place of 7th character of a code
  • Laterality (body side affected) is identified in the code description
  • Two types of excludes (ecxlude1 and exclude2)
  • More number of combination codes