2018 ICD-10 CM (Clinical Modification) complete reference online.
ICD 10 CM has been updated to reflect the current clinical understanding and technological advancements of medicine, and the code descriptions are designed to provide a more consistent level of detail. It contains a more extensive vocabulary of clinical concepts, body part specificity, patient encounter information, and other components from which codes are built.
The ICD 10 CM is divided into 21 chapters. The first character of the ICD code is a letter, and each letter is associated with a particular chapter, except for the letter "D", which is used in both Chapter 2 (Neoplasms) and Chapter 3 (Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism), and the letter "H", which is used in both Chapter 7 (Diseases of the eye and adnexa) and Chapter 8 (Diseases of the ear and mastoid process).