Learning about Current Procedural Terminology (CPT) codes

While I’ve loved learning about medical knowledge and technical skills in medical school and residency, one area I’m looking forward to learning more about is billing and coding. Current Procedural Terminology (CPT) codes are used to keep track of medical services and procedures for reimbursement in the United States, and make up one component of billing and coding. This made me wonder how CPT was established and how it evolved.

Medical coding emerged in the U.S. as early as 1872 when the Nomenclature of Diseases was published by the American Medical Association (AMA).¹ However, the first edition of CPT was not published until 1966 by the AMA, and it mainly covered surgical procedures. Subsequent editions in the 1970s expanded to cover a range of services in anesthesia, radiology, laboratory, pathology and medicine.¹ In the 1980s, CPT became the standard for reporting services to Medicare, state Medicaid programs, and outpatient hospital surgical procedures^1,2 before becoming the national coding standard for reporting medical services and procedures in 2000 under the Health Insurance Portability and Accountability Act.^1-3 CPT has continued to be maintained and updated by the AMA through the CPT Editorial Panel.³

The current edition of CPT uses 5-digit codes divided into three categories.³ Category I ranges from 00100-99499, with each code describing a specific medical procedure or service.³ For example, 99396 is the code for physical checkup for adults between 40 and 64 years old.⁴ Category II codes are for optional performance measurements, and Category III codes are for temporary data collection that assesses new procedures and services.³ CPT and its associated work, Relative Value Units (RVUs), are attached to visits to report medical services for reimbursement and administrative management, as well as productivity and performance analysis.^3,6 Total RVUs are based on work RVUs, practice expense RVUs, and malpractice RVUs,⁹ and are adjusted based on geographic practice cost and a conversion factor, which multiplies the RVU by a dollar amount.⁵

One subset of CPT codes is evaluation and management (E/M) codes. This subset is based on evaluation and management, or on time if more than 50% of the time was spent on patient counseling and care coordination.^7-9 For E/M services, codes depend on setting and level of medical decision-making (MDM), which can be straightforward, moderate or high.⁹ For example, 99202 is for a straightforward MDM or 15-minute office or other outpatient services visit that is equal to 0.93 RVUs.⁹ Modifiers such as GT or 95 for telemedicine, can be added to CPT codes.¹⁰ In 2021 and 2023, documentation of history and physical exams were no longer required for E/M code level selection.⁸

While figuring out CPT codes can be complicated, the Office of Johns Hopkins Physicians offers resources for healthcare professionals through the Professional Billing, Coding, Risk Adjustment Education website. Johns Hopkins MyLearning also has billing and coding learning modules available.^11,12

I am looking forward to learning more about CPT throughout the rest of my residency!

References

1. Borman KR. Chapter 1. Medical Coding in the United States: Introduction and Historical Overview. In: Savarise M, Senkowski C, eds. (2017). Principles of coding and reimbursement for surgeons (No. 25478). Switzerland: Springer International Publishing; 2017. Accessed June 14, 2025.
2. Dotson P. CPT® codes: what are they, why are they necessary, and how are they developed? Adv Wound Care (New Rochelle). 2013 Dec;2(10):583-587. doi: 10.1089/wound.2013.0483.
3. American Medical Association. CPT Overview and Code Approval. Accessed June 14, 2025. https://www.ama-assn.org/practice-management/cpt/cpt-overview-and-code-approval
4. B&SC Blog Team. Exploring Medical Coding as a Career? Learn More About Common CPT Codes. Bryant & Stratton College. October 16, 2024. Accessed June 14, 2025. https://www.bryantstratton.edu/blog/healthcare-degrees/exploring-medical-coding-as-a-career-learn-more-about-common-cpt-codes/.
5. Kantner AC. Understanding and improving your work RVUs. Family Practice Management. March 13, 2023. Accessed June 15, 2025. https://www.aafp.org/pubs/fpm/issues/2023/0300/understanding-rvus.html.
6. American Medical Association. Relative Value Units. Accessed June 15, 2025. https://cpt-international.ama-assn.org/relative-value-units
7. Patel HP, Ahadi NJ. Chapter 8. Basics of Billing and Coding: A Primer for the New Hospitalist Attending. In: Habicht R, Gulati M, eds. Hospital Medicine. Springer, Cham; 2017. Accessed June 15, 2025. https://doi.org/10.1007/978-3-319-49092-2_8
8. American Academy of Family Physicians. Coding for Evaluation and Management Services: Answers to Common Questions. AAFP.org. Accessed June 16, 2025. https://www.aafp.org/family-physician/practice-and-career/getting-paid/coding/evaluation-management.html
9. American Academy of Family Physicians. Time and Medical Decision Making Levels for Evaluation and Management Services. AAFP.org. Accessed June 16, 2025. https://www.aafp.org/family-physician/practice-and-career/getting-paid/coding/evaluation-management/time-and-medical-decision-making-levels-evaluation-and-management.html
10. Smith S. What are modifiers in medical billing? Sept 25, 2023. Accessed June 16, 2025. https://www.devry.edu/blog/modifiers-in-medical-billing.html
11. Office of Johns Hopkins Physicians. Professional Billing, Coding, Risk Adjustment Education. Accessed June 16, 2025. https://www.hopkinsmedicine.org/office-of-johns-hopkins-physicians/education-training/billing#codingalert
12. Johns Hopkins University of Medicine. Learning Search. Accessed June 16, 2025. https://johnshopkins.csod.com/ui/lms-learner-search/search?pageNumber=1&query=billing

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