Medical Coding Practice Test 2025 – Comprehensive All-in-One Guide to Success!

The coding system primarily used in the United States for diagnosing conditions is the ICD-10-CM (International Classification of Diseases, Tenth Revision, Clinical Modification). This system was implemented to provide a more detailed and specific set of codes for diagnoses compared to its predecessor, ICD-9-CM.

ICD-10-CM allows for the inclusion of a greater number of codes and provides more comprehensive classifications that can reflect the complexity of many medical conditions. This includes the ability to specify laterality (i.e., which side of the body is affected) and to include other details that can offer more context about the patient's condition, which is beneficial for healthcare providers in terms of treatment and for insurers in terms of reimbursement.

The other coding systems mentioned have different primary functions. CPT (Current Procedural Terminology) is used mainly for coding medical services and procedures, while HCPCS (Healthcare Common Procedure Coding System) includes codes for products, supplies, and non-physician services. ICD-9-CM was previously used for diagnoses but has since been replaced by ICD-10-CM in the U.S. medical coding environment to improve specificity and accuracy in healthcare documentation and billing.