What are ICD-10 codes, and how are they used?

Coding has become an increasingly sought-after skill in a number of industries. Healthcare is no exception—though it’s a slightly different type of coding. Medical codes are translations of the notes providers take for each patient into a standardized form, according to Brian Stein, Rush University Medical Center’s chief quality officer. Those codes are used for multiple reasons, such as tracking diseases and figuring out how much to pay providers.

Say your doctor writes that you have the flu in your electronic health record (EHR). That diagnosis has its own code—a set of numbers or a combination of numbers and letters—called an ICD-10-CM code. ICD codes are just one type of medical code and are mainly used for billing.

ICD stands for International Classification of Diseases. The “10” means the current codes in use are the 10th version, and the CM indicates that it is a “clinical modification,” or diagnosis code.

After your appointment, the ICD-10-CM code is stored in your EHR and sent to insurers, who use it to help determine how to pay your doctor for diagnosing you. Health authorities like the CDC also use the code to help track how many cases of the flu happened this year.

There’s another type of ICD-10 code called ICD-10-PCS. The PCS means procedure codes, and they indicate what a provider did to treat you. Say a doctor diagnoses you with dehydration and treats you with IV fluids. The ICD-10-PCS code would say that the provider gave you IV fluids. This is again stored in your EHR and sent to insurers to tell them what they should be paying the provider for doing.

There’s about 70,000 ICD-10-CM codes and 70,000 ICD-10-PCS codes.