Screening Colonoscopy That Turns Therapeutic
A 68-year-old Medicare beneficiary with no GI symptoms and no family history presents for a screening colonoscopy. The physician documents 'average-risk screening for colorectal cancer,' reaches the cecum, finds a 12 mm sessile polyp in the transverse colon, and removes it by snare polypectomy. Total procedure time is 22 minutes, and moderate sedation is administered by the endoscopist. The facility coder must build the claim and explain the patient's financial liability. The charge master lists 45378 (colonoscopy, diagnostic) and 45385 (colonoscopy with snare polypectomy). The hospital maps GI endoscopy to revenue code 0490.
1. Which CPT code and which diagnosis codes go on the claim, and in what order?
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Procedure: report 45385 (colonoscopy with snare polypectomy) - not 45378, and not both. The polyp removal is the definitive service performed and it supersedes the diagnostic code. Append modifier PT to signal that a colorectal cancer screening test was converted to a therapeutic procedure; the hospital outpatient claim carries 45385-PT on revenue code 0490.
Diagnoses, in this order:
- Z12.11 - encounter for screening for malignant neoplasm of colon (first-listed).
- D12.6 - benign neoplasm of colon, unspecified (the finding).
Why the screening code stays first: when a screening colonoscopy becomes diagnostic or therapeutic and the procedure is reported with modifier PT for Medicare, the screening code remains first-listed and the finding is secondary. Reversing the order (D12.6 first) misrepresents the encounter as a problem-driven colonoscopy, changes the benefit category, and is a frequent target of medical-review audits. If a second polyp had been removed by a different technique, only the most resource-intensive technique is reported once - never both 45385 and 45380.
2. Should an ABN have been issued, and how do you explain the patient's liability?
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No ABN. An ABN is for items or services the hospital expects Medicare to deny as not medically necessary. A screening colonoscopy that becomes therapeutic is covered; issuing an ABN here would be inappropriate, and asking the patient to sign one before a covered screening is a beneficiary-notice compliance problem.
Liability explanation:
- With modifier PT, the Part B deductible is waived because the service originated as a covered screening.
- Coinsurance for the therapeutic portion may still apply, so the patient is not necessarily at zero liability. Confirm the current Medicare guidance and your MAC's instruction before quoting a dollar amount to the patient or to registration staff.
The practical rule for the front desk: do not collect a screening colonoscopy coinsurance up front as if it were diagnostic, and do not tell the patient 'everything is covered' either. The correct statement is that the deductible is waived and any coinsurance will be determined after the procedure and its findings are coded.
3. If the patient had instead presented with hematochezia and the polyp was found during that workup, how would the coding and the PT modifier change?
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The encounter is no longer a screening, so the screening framework collapses entirely.
- Drop modifier PT. The PT modifier exists only for a screening test converted to diagnostic or therapeutic; on a symptom-driven colonoscopy it is invalid.
- Diagnosis order changes: K92.1 (melena/hematochezia - code to the specific documented symptom) first-listed, with D12.6 secondary. Z12.11 is not reported at all.
- Procedure remains 45385, and 45378 is still not separately reported.
- Liability changes: no screening benefit applies, so the deductible and coinsurance follow ordinary diagnostic rules, and the patient's out-of-pocket exposure is materially different from the screening scenario.
This is why the coder must read the indication in the body of the note rather than the scheduler's 'screening' label: the same procedure code, same polyp, and same physician can produce two completely different claims depending on why the scope was done.