Which coding system is used to report diagnoses in U.S. medical billing?

• A. ICD-10-CM
• B. CPT
• C. HCPCS Level II
• D. ICD-10-PCS

Answer: (A)

Diagnoses in U.S. medical billing are reported using ICD-10-CM. This system converts a patient’s diseases, conditions, symptoms, and other health problems into standardized codes that insurers use for claims and reimbursement. The other options serve different purposes: CPT codes describe procedures and services performed by clinicians; HCPCS Level II codes cover supplies, equipment, and some nonphysician services; ICD-10-PCS codes inpatient procedures, detailing what was done during a hospital stay. Since the question is about reporting diagnoses, ICD-10-CM is the appropriate coding system.