Screening Colonoscopy Turns Therapeutic: Payer Rules and Modifier Selection
Mr. Lee, a 62-year-old Medicare beneficiary, undergoes a screening colonoscopy at a hospital-based ambulatory surgical center. He has no personal history of colorectal cancer, polyps, or inflammatory bowel disease, and he meets average-risk screening criteria. During the colonoscopy, the gastroenterologist finds a 12-mm sessile polyp in the transverse colon and removes it completely by snare polypectomy. No other polyps or lesions are seen. The physician documents 'screening colonoscopy converted to diagnostic polypectomy.' The anesthesia service is provided by an anesthesiologist and is billed separately. The ASC and the gastroenterologist will submit separate claims. The patient has met his Part B deductible for the year. The coder must determine the professional and facility codes, the correct modifier, and whether the patient can be billed coinsurance for the polypectomy.
1. Assign the professional CPT code and modifier for the gastroenterologist’s service. Explain the screening-to-diagnostic conversion and payer rules.
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Professional: 45385-PT. 45385 is colonoscopy with removal of a tumor, polyp, or lesion by snare technique. The procedure began as a screening colonoscopy, but the polypectomy made it diagnostic. For Medicare, append modifier PT (colorectal cancer screening test converted to diagnostic test or other procedure) to 45385. The PT modifier tells Medicare that the service started as a screening and was converted, which preserves the screening benefit and prevents inappropriate coinsurance. Do not report G0121 (screening colonoscopy) because G0121 does not include polypectomy. For a commercial payer, modifier 33 (preventive service) would typically be used instead of PT; the payer’s policy controls. Only one code is reported for the colonoscopy because the polypectomy is the definitive service.
2. How should the ASC facility claim be coded? Does the ASC use the same code and modifier? Explain.
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The ASC facility claim should report 45385-PT for the facility service. The ASC uses CPT codes for the facility component; the PT modifier communicates that the screening colonoscopy was converted to a diagnostic polypectomy. The facility should not report G0121 because the service included a polypectomy, which is not covered by the screening code. The professional and facility claims are separate: the physician bills professional services, and the ASC bills the facility service. Both claims should carry the same procedure code and PT modifier. The anesthesia claim is separate and should be coded by the anesthesia provider. If the payer requires a different modifier for the facility claim, follow the payer’s instructions, but PT is the Medicare standard.
3. Suppose Mr. Lee had a personal history of colon polyps and the procedure was scheduled as surveillance, not screening. How would the coding and patient responsibility change?
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If the indication is surveillance for personal history of colon polyps, the service is diagnostic, not a screening test. Report 45385 without modifier PT (and without modifier 33 for commercial payers). Add Z86.010 (personal history of colonic polyps) as the diagnosis. Because this is not a screening service, the Medicare coinsurance and deductible rules apply; the patient may owe coinsurance. An ABN is not automatically required for a medically necessary surveillance colonoscopy, but if the coder believes the service may not be covered, an ABN should be considered before the service. The key judgment is the indication: average-risk screening triggers PT; surveillance for prior polyps does not.