ICD-10 Codes

Representation of ICD-10 Diagnosis Codes

In practice, ICD-10 diagnoses are represented by 3- to 5-character codes with explicit decimals. Each code begins with an alphabetic character that generally corresponds to the ICD-10 chapter:

Code	Chapter
A-B	Infectious and parasitic diseases
C	Malignant neoplasms
D00-D09	In situ neoplasms
D50-D89	Diseases of blood, blood-forming organs, immune mechanism
E	Endocrine, nutritional, and metabolic disease
F	Mental and behavioral disorders
G	Diseases of the nervous system
H00-H59	Diseases of the eye and adnexa
H60-H95	Diseases of the ear and mastoid process
I	Diseases of the circulatory system
J	Diseases of the respiratory system
K	Diseases of the digestive system
L	Diseases of skin and subcutaneous tissue
M	Diseases of the musculoskeletal system and connective tissue
N	Diseases of the genitourinary system
O	Pregnancy, childbirth, and the puerperium
P	Certain conditions originating in the perinatal period
Q	Congenital malformations, deformations, and chromosomal abnormalities
R	Symptoms, signs, and abnormal clinical and laboratory findings, not elsewhere classified
S-T	Injury, poisoning, and certain other consequences of external causes
V-Y	External causes of morbidity and mortality
Z	Factors influencing health status and contact with health services