Free gastroenterology coding tool
Colonoscopy coding and cost outcome tool
Four questions, and it returns the code, the modifier, the diagnosis order, and what the patient will actually be charged. Runs entirely in your browser. There is no field to enter patient information into, by design.
Part of the gastroenterology billing page.
Procedure code
G0121
Medicare screening. G0121 for average risk. Do not use CPT 45378 on a screening claim. CMS Medicare Claims Processing Manual, Chapter 18, Section 60.2.
Modifier
None on the G-code (screening is in the descriptor)
No modifier on the Medicare G-codes. Modifier 33 is not used on G0121 or G0105. CMS Medicare Claims Processing Manual, Chapter 18, Section 60.2.
Diagnosis sequencing
Z12.11 (encounter for screening for malignant neoplasm of the colon) in the first position. The finding goes second. Per ICD-10-CM Coding Clinic, the screening code is listed first even where a procedure results from it. ICD-10-CM Coding Clinic.
Anesthesia note
Report 00811 with modifier PT for a screening that converts. For a screening that stays screening the base is 00812 (3 base units). CMS Coverage Article A55069.
What the patient pays
Nothing. Screening colonoscopy is covered with no patient cost-sharing.
Note
After a positive FIT, FOBT or Cologuard result, the follow-up colonoscopy is covered as screening with no cost-sharing. Effective 31 May 2022 for ACA plans and 1 January 2023 for Medicare. For a Medicare beneficiary in this pathway, report G0105 or G0121 with the KX modifier. Consolidated Appropriations Act 2021, Section 122.
Educational reference only. Not coding, billing, legal or medical advice. Rules change. Verify against current CMS guidance, AGA and ACG resources, and the specific payer policy. No patient information is collected or transmitted. This tool runs entirely in your browser; nothing you select leaves this page.