Screening Colonoscopy That Becomes Therapeutic
A 62-year-old average-risk Medicare patient presents for a screening colonoscopy; the order sheet carries Z12.11. The endoscopist advances to the cecum with a good prep. In the transverse colon a 12-mm sessile polyp is removed by snare polypectomy and retrieved. In the sigmoid colon a separate 5-mm polyp is sampled with cold forceps and left in place. Total procedure time is 22 minutes with no complications. Moderate sedation is administered by the endoscopist. The patient has no GI symptoms, no iron-deficiency anemia, and no family history of colorectal cancer. The charge sheet prepared by the front desk lists both 45385 and 45380 and asks the Coder to 'drop the screening code since we found a polyp.'
1. What CPT/HCPCS code(s) and modifiers do you report, and with what diagnosis sequence?
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Report one procedure code: 45385-PT (Colonoscopy, flexible; with removal of tumor(s), polyp(s), or other lesion(s) by snare technique) with modifier PT (colorectal cancer screening test converted to diagnostic test or other procedure) for the Medicare claim.
Diagnoses, in order:
- D12.3 - benign neoplasm of transverse colon (the lesion that was actually removed, and the reason the study became diagnostic).
- D12.5 - benign neoplasm of sigmoid colon.
- Z12.11 - encounter for screening for malignant neoplasm of colon, retained as an additional code to explain why the study was performed.
Sequencing logic: once a polyp is found and treated, the screening code no longer describes the encounter and moves out of first position. The 'screening' status still matters for the payer, which is why Z12.11 stays on the claim and why modifier PT is appended rather than dropping the screening history altogether.
2. Should 45380 also be billed for the sigmoid biopsy? Defend your answer.
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No. A colonoscopy is reported once per session. When several interventions are performed through the same scope, the single code that describes the most comprehensive service is reported; lesser interventions performed in the same session are not separately billable and are also bundled under the NCCI procedure-to-procedure edits.
What 45385 already describes is a snare polypectomy. The cold-forceps sampling of a second, separate polyp is a component of the same endoscopic session and is not separately payable. Adding 45380 would:
- duplicate the surgical approach,
- conflict with the once-per-session reporting rule, and
- likely trigger an NCCI denial (CO-97) and a documentation request.
If the sigmoid lesion had been snared and removed rather than biopsied, the answer would be the same: still one code, still 45385.
3. The front desk wants the screening code billed instead, arguing the patient's coinsurance will be lower. How do you respond?
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The coding decision cannot be driven by the patient's financial liability. Code selection is governed by what was performed and documented. A snare polypectomy was performed, so the therapeutic colonoscopy code with modifier PT is the accurate claim.
Consequences of billing G0121 (screening colonoscopy, average risk) here:
- It misstates the service rendered - the claim would not match the operative report, creating a false-claim exposure even though the intent was benign.
- Medicare's screening benefit structure changes when a screening converts to diagnostic; the payer applies that rule based on accurate coding, not on what the practice wishes the coinsurance to be.
Correct response: explain that modifier PT exists precisely to tell the Medicare contractor the test began as a screening and became diagnostic, so the contractor - not the practice - applies the cost-sharing rules. Offer the patient the practice's financial-counseling route. Also note that commercial payers vary: some recognize modifier 33 rather than PT, which is a contract question to resolve before the claim drops, not after.