Gastroenterology CPT Codes
Gastroenterology CPT codes sit mostly in the Surgery section under Digestive (40490–49999). Endoscopy codes are strictly hierarchical: when a therapeutic procedure happens during the same session as a diagnostic exam, only the therapeutic code gets billed. Bundling rules decide almost everything in GI billing, so they're worth learning cold.
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Gastroenterology CPT codes
Colonoscopy, Diagnostic
Flexible colonoscopy to cecum for diagnosis. If therapeutic procedure performed, upgrade to appropriate code.
Colonoscopy with Biopsy
Colonoscopy with one or more biopsies. Replaces 45378 when tissue is taken.
Colonoscopy with Snare Polypectomy
Colonoscopy with polyp removal by snare. Common for polyp surveillance and colorectal cancer prevention.
Colonoscopy with Directed Submucosal Injection
Submucosal injection to lift lesion prior to removal. Often paired with polypectomy.
Upper GI Endoscopy, Diagnostic
Esophagogastroduodenoscopy (EGD) without biopsy or therapeutic intervention.
Upper GI Endoscopy with Biopsy
EGD with biopsy of mucosa. Common for H. pylori sampling, celiac evaluation, Barrett's surveillance.
Upper GI Endoscopy, Foreign Body Removal
EGD with removal of a foreign body from esophagus or stomach.
Codes in blue have full detail pages with documentation requirements, billing mistakes, and FAQ.
Gastroenterology billing notes
Colonoscopy codes are hierarchical. Take a biopsy (45380) or remove a polyp (45385), and the diagnostic code 45378 disappears into it. Bill only the highest-level procedure performed.
Medicare screening colonoscopies use G-codes: G0105 for high-risk patients, G0121 for average risk. Billing 45378 for a screening changes what the patient owes, and they'll call you about it.
A screening that finds and removes a polyp converts to a therapeutic code like 45385. Append modifier PT for Medicare (33 for commercial payers) to keep most of the patient's screening cost protections intact.
Upper endoscopy codes (43235–43259) follow the same hierarchy as colonoscopies. Diagnostic bundles into therapeutic, one code per session.
Anesthesia bills separately from the procedure. An anesthesiologist's propofol sedation has its own code and claim, while moderate sedation by the endoscopist follows different rules entirely.
Frequently asked questions about gastroenterology billing
Why can't I bill 45378 and 45385 together?▼
Because 45385 already includes the full colonoscopy. The codes are hierarchical: the diagnostic exam is bundled into any therapeutic colonoscopy code from the same session. Bill only the highest-level procedure performed, or the claim comes back with an unbundling denial.
What happens when a screening colonoscopy finds a polyp?▼
The procedure converts from screening to therapeutic, billed as 45385 (or 45380 for biopsy) with modifier PT for Medicare or modifier 33 for commercial payers. Those modifiers preserve most of the patient's screening cost protections, though Medicare patients may still owe some coinsurance after the conversion.
Is anesthesia billed separately from the colonoscopy?▼
Yes. The GI physician bills the procedure, and the anesthesia provider bills their own code (typically 00812 for screening). Moderate sedation given by the endoscopist follows different rules, and payer policies on separate anesthesia coverage for average-risk screenings vary, so verify before scheduling.
Sources
- Code set structure and updates: American Medical Association — CPT
- Fee schedule and component billing rules: CMS Medicare Physician Fee Schedule
- How we research and verify: our editorial policy
CPT® is a registered trademark of the American Medical Association. Content on this page is original educational writing, not a reproduction of AMA-copyrighted descriptions. Verify codes and payer rules before billing.