Medicare AdvantageBilling CodesHigh impact
Coding Follow-Up Colonoscopies Correctly for Medicare Advantage Members
Medical Mutual of Ohio·Gastroenterology, General Surgery, Family Medicine +1 more·Coding
We identified it
Jun 20, 2026
Summary
Medicare Advantage members must have follow-up colonoscopies after positive stool-based tests coded as screening (G0105/G0121) with modifier KX to ensure $0 member cost-sharing. If biopsy/polypectomy is performed during the same visit, append modifier PT to the therapeutic CPT code as secondary.
Action Required
Immediately: Billing team must update coding workflows to use G0105 or G0121 with modifier KX for follow-up colonoscopies after positive stool tests for Medicare Advantage members. When biopsy/polypectomy occurs during screening colonoscopy, append modifier PT to the therapeutic CPT code (not the G-codes). Update billing system edits and train staff on proper modifier usage to prevent inappropriate member cost-sharing.