A Fellow's Introduction to ICD-10 and CPT Codes
Welcome back to the GI Billing Playbook, your guide to navigating the business of medicine as you prepare for your career. As you master complex procedures and diagnostic challenges during fellowship, it's equally important to begin learning the language of healthcare finance. This language is built on two fundamental code sets: ICD-10 and CPT codes. These codes form the basis for risk adjustment and both fee-for-service and value-based payment systems. Becoming familiar with them will help you receive proper reimbursement.
The International Classification of Diseases, 10th Revision (ICD-10) is a standardized system of diagnostic codes used across healthcare. Following its adoption in the U.S. in 2015, the system expanded from approximately 14,000 codes under ICD-9 to roughly 70,000 codes, allowing for far greater specificity in describing a patient's condition. For every service you provide, an ICD-10 code must be linked to justify medical necessity. For instance, documenting "GERD with esophagitis" allows for the use of a more specific code (K21.0) than a simple "GERD" diagnosis (K21.9). This specificity is important because ICD-10 codes translate what is documented so that risk adjustment can be captured through billing. Accurate risk adjustment more precisely captures the severity of illness and risk of mortality scores for inpatients, which can then secure more appropriate overall payment for the hospital. Furthermore, by reflecting the complexity of the patient population being managed, robust risk adjustment can positively influence a hospital's rankings in crucial benchmarking systems like the CMS STARs program and Vizient.
Current Procedural Terminology (CPT) codes are maintained by the American Medical Association (AMA), this set of approximately 10,000 codes describes every medical service or procedure you perform. For GI fellows, these fall into two main categories: Evaluation & Management (E&M) service codes and procedure codes. Common E&M CPT codes you will need to be familiar with include 99221-99223 for Initial Hospital or Observation visits, 99231-99233 for subsequent hospital visits, 99202-99205 for new outpatient visits, and 99212-99215 for established outpatient visits. On the procedural side, core gastroenterology codes include 43235 for a diagnostic EGD, 43239 for an EGD with biopsy, 43244 for an EGD with variceal ligation, 43259 for EUS, 43274 for ERCP with stenting, 45380 for a colonoscopy with biopsy, and 45385 for a colonoscopy with polypectomy.
Work Relative Value Units (wRVUs) are the core metric that translate your day-to-day clinical work into “productivity” and, in many first contracts, directly into how you get paid, so understanding them early is critical for new GI attendings. Each CPT code you bill—whether a colonoscopy, EGD, or clinic visit—carries a specific wRVU value intended to reflect the time, technical skill, mental effort, and risk associated with that service, and your total annual wRVUs become a key benchmark used by hospitals and groups to compare your output against GI peers and national norms. Because many gastroenterology employment agreements link compensation to a dollar amount per wRVU, with base salary expectations and bonuses tied to hitting certain wRVU thresholds, understanding how your procedure and clinic mix generates wRVUs empowers you to evaluate offers, set realistic volume expectations, and advocate for a practice model that aligns with how you want to care for patients. For fully employed physicians, for example, contracts typically specify minimum wRVU thresholds to maintain base salary and additional tiers above which “productivity” bonuses are calculated, making fluency in wRVUs essential to both financial planning and practice design as you transition into independent practice.
Here are some common CPT codes and their 2026 wRVUs.
By understanding the interplay of ICD-10, CPT, and wRVUs, you begin to reframe how your clinical work is quantified and valued, translating the expert services you perform and meticulously document into the data that drives both practice reimbursement and personal compensation.
Author
Edward Sun, MD, MBA, FASGE, is Associate Medical Director at Peconic Bay Medical Center. Dr. Sun serves as Chair of the ASGE Reimbursement Committee.