How Does the ICD-10 Coding System Work?

Codes used in the International Classification of Diseases, 10th Edition, ICD-10, contain between three and seven characters, explains the American Health Information Management Association. The first three characters refer to broad categories, while the remaining characters provide additional details about the diagnosis.

In this coding system, the lead character is always a letter, and it gives the most general information about the diagnosis. Moving to the right, each character provides more detailed information about the diagnosis and quality of care.

WebPT explains that in the code S86.011 D, the "S" refers to "injury, poisoning and certain other consequences of external causes related to single body regions." The next two digits, 86, reveal that the injury involves soft tissue of the lower leg. Moving on to the next three digits, the "0" means the injury involved, specifically, the Achilles tendon. The first "1" says that injury is a sprain, and the second "1" confirms that it is on the right side of the body. The seventh and last character, the extension, gives information about the episode or quality of care.

The United States is the last developed country to begin using the ICD-10, explains an article posted by the American Academy of Orthopaedic Surgeons. Other countries had already been using the 10th edition for 12 years, as of 2013.