Which coding system is primarily used for outpatient clinic visits in the U.S.?

• A. DSM-5 for diagnosis and CPT/HCPCS for procedures
• B. ICD-10-CM for diagnosis and CPT/HCPCS for procedures
• C. ICD-9-CM for both diagnosis and procedures
• D. ICD-10-PCS for diagnosis

Answer: (B)

Outpatient billing uses a two-part coding approach: ICD-10-CM codes for the patient's diagnoses and CPT/HCPCS codes for the services or procedures performed during the visit. ICD-10-CM is the diagnosis coding system used across most U.S. healthcare settings since ICD-10 replaced ICD-9-CM for diagnoses. For the actual services, CPT codes describe physician procedures and tests, while HCPCS Level II codes cover items and services not included in CPT. ICD-10-PCS is reserved for inpatient procedures, not outpatient encounters, and DSM-5 is a diagnostic manual for mental disorders, not a medical billing coding system. So, using ICD-10-CM for diagnoses with CPT/HCPCS for procedures correctly reflects how outpatient clinic visits are coded.