The International Statistical Classification of Diseases and Health Related Problems (ICD) was published by the World Health Organization (W.H.O).

The International Classification of Diseases (ICD) is designed to promote international comparability in the collection, processing, classification, and presentation of mortality statistics. This includes providing a format for reporting causes of death on the death certificate. The reported conditions are then translated into medical codes through use of the classification structure and the selection and modification rules contained in the applicable revision of the ICD, published by the World Health Organization (WHO). These coding rules improve the usefulness of mortality statistics by giving preference to certain categories, by consolidating conditions, and by systematically selecting a single cause of death from a reported sequence of conditions. The single selected cause for tabulation is called the underlying cause of death, and the other reported causes are the nonunderlying causes of death. The combination of underlying and nonunderlying causes is the multiple causes of death.

The ICD has been revised periodically to incorporate changes in the medical field. The Tenth Revision (ICD-10) differs from the Ninth Revision (ICD-9) in several ways although the overall content is similar: First, ICD-10 is printed in a three-volume set compared with ICD-9's two-volume set. Second, ICD-10 has alphanumeric categories rather than numeric categories. Third, some chapters have been rearranged, some titles have changed, and conditions have been regrouped. Fourth, ICD-10 has almost twice as many categories as ICD-9. Fifth, some fairly minor changes have been made in the coding rules for mortality.

Work on ICD-10 began in 1983, and the new revision was endorsed by the Forty-third World Health Assembly in May 1990. The latest version came into use in WHO Member States starting in 1994.The classification system allows more than 155,000 different codes and permits tracking of many new diagnoses and procedures, a significant expansion on the 17,000 codes available in ICD-9.Adoption was relatively swift in most of the world. Several materials are made available online by WHO to facilitate its use, including a manual, training guidelines, a browser, and files for download. Some countries have adapted the international standard, such as the "ICD-10-AM" published in Australia in 1998 (also used in New Zealand). and the "ICD-10-CA" introduced in Canada in 2000.

Adoption of ICD-10 has been slow in the United States. Since 1979, the USA had required ICD-9-CM codes for Medicare and Medicaid claims, and most of the rest of the American medical 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. Meanwhile, NCHS received permission from the WHO to create a clinical modification of the ICD-10, and has production of all these systems

The ICD provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. Every health condition can be assigned to a unique category and given a code, up to six characters long. Such categories can include a set of similar diseases. The ICD is revamped periodically and is currently on the tenth edition(ICD-10). The next update (ICD-11) will be out sometime in 2011. Below is a short list of codes and there matching diagnoses categories.

Chapter
Blocks
Title

I
A00-B99
Certain infectious and parasitic diseases

II
C00-D48
Neoplasms

III
D50-D89
Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism

IV
E00-E90
Endocrine, nutritional and metabolic diseases

V
F00-F99
Mental and behavioural disorders

VI
G00-G99
Diseases of the nervous system

VII
H00-H59
Diseases of the eye and adnexa

VIII
H60-H95
Diseases of the ear and mastoid process

IX
I00-I99
Diseases of the circulatory system

X
J00-J99
Diseases of the respiratory system

XI
K00-K93
Diseases of the digestive system

XII
L00-L99
Diseases of the skin and subcutaneous tissue

XIII
M00-M99
Diseases of the musculoskeletal system and connective tissue

XIV
N00-N99
Diseases of the genitourinary system

XV
O00-O99
Pregnancy, childbirth and the puerperium

XVI
P00-P96
Certain conditions originating in the perinatal period

XVII
Q00-Q99
Congenital malformations, deformations and chromosomal abnormalities

XVIII
R00-R99
Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified

XIX
S00-T98
Injury, poisoning and certain other consequences of external causes

XX
V01-Y98
External causes of morbidity and mortality

XXI
Z00-Z99
Factors influencing health status and contact with health services

XXII
U00-U99
Codes for special purposes
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http://www.who.int/classifications/apps/icd/icd10online/

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