What type of codes are identified by the letter "C" in the coding system?

The codes identified by the letter "C" in the coding system are known as Outpatient Procedure Payment System (OPPS) codes. These are specific to the Medicare outpatient payment system, which governs how facilities are reimbursed for outpatient services. The letter "C" designates these codes to clearly differentiate them within the larger coding framework, including the Current Procedural Terminology (CPT) and the Healthcare Common Procedure Coding System (HCPCS).

OPPS codes play a critical role in defining which outpatient services are covered and how much providers can expect to be reimbursed for these services. They help standardize payments and ensure appropriate compensation for specific outpatient procedures performed in a hospital setting.

In the context of the other options, diagnosis codes are usually represented by a different set of alpha characters (typically "I" for ICD-10-CM), while procedure codes may utilize CPT codes, which do not begin with "C." The outpatient procedure codes and OPPS codes refer to similar concepts but are specifically indicated by the designation of "C," aligning them more closely with the payment systems used by Medicare rather than just classifying them as procedure codes in general.