CPT Code 45385: Colonoscopy With Snare Polypectomy (2026 Billing and Modifier Guide)

When Do You Bill CPT 45385?

CPT code 45385 is a gastroenterology procedure code that reports a flexible colonoscopy with removal of one or more polyps, tumors, or lesions by snare technique, using a cold or hot snare. It is the most common colonoscopy polypectomy code, and it replaces the diagnostic colonoscopy code 45378 the moment a polyp is snared. Report it once per session no matter how many polyps are removed by snare, and select a modifier if the colonoscopy began as a screening.

It replaces 45378: Once any polyp is removed, the procedure is therapeutic and 45378 no longer applies. You bill 45385, not both.

Screening changes the modifier: If a screening colonoscopy finds and removes a polyp, add modifier PT for Medicare or modifier 33 for commercial plans to protect the patient’s screening benefit.

Report it once: One 45385 covers every polyp removed by snare in the session. A polyp removed by a different technique at a separate site may bill separately with modifier 59 or XS.

What Is CPT Code 45385?

CPT 45385 is where colonoscopy billing gets expensive to get wrong. A screening that finds a polyp converts to a therapeutic procedure roughly 35% to 40% of the time, and that conversion is the single most error-prone moment in gastroenterology billing. Misclassify it, cross the screening modifiers, or undercode an advanced resection as a simple snare, and you either lose revenue or hand the patient a bill they should never have received.

The colonoscopy family follows a base-plus-upgrade logic. 45378 is the base diagnostic code. The moment an intervention happens, the code upgrades to whatever was actually performed. For snare polypectomy, that upgrade is 45385. For cold biopsy forceps, it is 45380. For endoscopic mucosal resection, it is 45390. The operative note and its documented technique govern the code, per the Tri-Society Coding Guide from ASGE, AGA, and ACG.

One question we hear constantly from gastroenterology practice managers is why their converted-screening claims keep getting denied. In our experience matching providers with billing partners, the answer almost always comes down to modifier handling: either PT was used on a commercial claim, 33 was used on a Medicare claim, or the modifier was omitted entirely. Each of those errors produces a different failure, and all of them are preventable with the right billing process in place.

When Do You Bill 45385 Instead of 45378 or 45380?

Bill 45385 when the endoscopist removes a polyp, tumor, or lesion by snare. Bill 45378 only when nothing is removed, and 45380 when tissue is sampled by cold biopsy forceps rather than snared. Report the single highest-level intervention: if a polyp is snared, 45385 is the code, and 45378 is replaced, not added.

CPT Code	Descriptor	Use When
45378	Diagnostic colonoscopy	Exam only, nothing removed
45380	Colonoscopy with biopsy	Tissue sampled by cold biopsy forceps
45384	Colonoscopy, removal by hot biopsy forceps	Polyp removed by hot forceps
45385	Colonoscopy, removal by snare	Polyp removed by cold or hot snare
45388	Colonoscopy with ablation	Lesion destroyed, no tissue removed
45390	Colonoscopy with endoscopic mucosal resection	Lift-and-cut resection of flat or sessile lesion

The trap at both ends is real. Undercoding an endoscopic mucosal resection as a simple 45385 loses meaningful revenue, since CMS added 45390 to colonoscopy billing guidance (MCD article A57342) effective October 1, 2024. At the same time, cauterizing a polypectomy site is bundled into 45385 and is not a separate bleeding-control charge. Per the Tri-Society Coding Guide from ASGE, AGA, and ACG, the operative note and its documented technique govern the code.

What Happens When a Screening Colonoscopy Finds a Polyp?

The procedure converts from screening to therapeutic, and the code upgrades to what was done, usually 45385 for snare polypectomy. You do not revert to the screening code. Instead, bill 45385 and add modifier PT for Medicare or modifier 33 for commercial plans so the claim is still recognized as a converted screening rather than a routine diagnostic procedure.

This conversion is the highest-risk moment in colonoscopy billing. For Medicare, a screening starts as G0105 for high-risk patients or G0121 for average-risk patients, not 45378. The instant a polyp is snared, the therapeutic CPT 45385 replaces the screening code and modifier PT signals the screening origin. For commercial and Medicaid plans, modifier 33 does the same job. Sequencing matters too: place the screening diagnosis Z12.11 first and the finding, such as K63.5 for a colon polyp, second, because the order can change whether the patient owes anything.

Across the billing companies we vet, the practices that handle this cleanly are the ones with a documented conversion workflow: the endoscopist flags the conversion in real time, the coder upgrades the code and applies the correct modifier before the claim drops, and the front desk adjusts the patient’s cost-sharing expectation before they leave. The practices that scramble are the ones where the conversion is caught after the claim is already submitted, and by then the denial is in motion.

Does the Patient Still Owe Money if a Polyp Is Removed?

For Medicare, yes, but a shrinking amount. When a screening colonoscopy removes a polyp, the deductible is waived and the patient’s coinsurance is being phased out: 15% from 2023 through 2026, 10% from 2027 through 2029, and 0% in 2030 and beyond. Commercial plans generally waive cost-sharing entirely under ACA preventive rules when modifier 33 is applied.

Year	Medicare Patient Coinsurance	Notes
2023 to 2026	15%	Deductible waived; modifier PT required
2027 to 2029	10%	Continued phase-down under the CAA 2021
2030 and after	0%	Fully covered, no coinsurance

This phase-down comes from the Consolidated Appropriations Act of 2021 and is confirmed in the American Gastroenterological Association screening colonoscopy coding guidance. The practical point for 2026 is that a Medicare patient whose screening removes a polyp still owes 15%, so front-desk teams should set that expectation before the procedure. What they should never owe is a full diagnostic bill caused by a missing modifier PT.

Which Modifiers Apply to CPT 45385?

Modifier selection on 45385 is dominated by the screening-to-therapeutic scenario, and one crossed modifier can either deny the claim or misbill the patient. The modifiers that matter:

Modifier PT (Medicare): For a screening colonoscopy converted to therapeutic. It waives the deductible and triggers the reduced screening coinsurance. Append it to 45385 on every Medicare converted-screening claim.

Modifier 33 (commercial and Medicaid): The preventive-services equivalent of PT. It signals screening intent so the plan applies ACA preventive coverage. Never use 33 on a Medicare claim or PT on a commercial claim, because crossing them draws automatic denials.

Modifier 59 or XS: Append to a second colonoscopy code when a distinct lesion is treated by a different technique at a separate site, such as a snare polypectomy plus a cold biopsy elsewhere. The note must name each site and technique.

Modifier 22: For an unusually difficult or complex polyp removal that required substantially more work, supported by documentation.

Modifier 53 or 52: For a discontinued or reduced procedure, for example a colonoscopy aborted for inadequate bowel preparation before the polyp could be removed.

How Much Does CPT 45385 Reimburse in 2026?

CPT 45385 pays roughly $270 to $300 for the physician’s professional work in a 2026 office (non-facility) setting, based on about 4.5 work RVUs and the non-qualifying-APM conversion factor of $33.40. In an ASC or hospital, the physician fee is lower because the facility bills its own fee separately.

Site of service drives the total. The ASC facility payment runs roughly 52% to 58% of the hospital outpatient rate for GI endoscopy, per the CMS OPPS and ASC final rule, and 45385 carries a 000-day global period, so no follow-up window is bundled in. When a second colonoscopy-family procedure is performed in the same session, the multiple endoscopy rule applies: the base diagnostic colonoscopy value (45378) is subtracted from the lower-valued code rather than paid twice. The 2026 conversion factor comes from the CMS CY2026 Physician Fee Schedule final rule (CMS-1832-F), and the qualifying-APM factor is slightly higher at $33.57.

Which ICD-10 Codes Support CPT 45385?

45385 must be linked to a diagnosis that justifies the procedure, and 2026 brought a notable change: the personal-history-of-colon-polyps code was expanded, so practices still using the old Z86.010 will see rejections. Current codes that support 45385 include:

Z12.11: Encounter for screening for malignant neoplasm of colon, sequenced first on a screening that converts to therapeutic.

K63.5: Polyp of colon, the finding code when a polyp is identified during the exam.

D12.6: Benign neoplasm of colon unspecified, when pathology confirms a benign neoplasm.

Z86.0100: Personal history of colon polyps unspecified, for surveillance colonoscopies, replacing the retired Z86.010.

Z86.0101: Personal history of adenomatous and serrated colon polyps, when the prior polyp type is documented.

Z83.719: Family history of colon polyps unspecified, supporting high-risk screening intervals.

Why Do CPT 45385 Claims Get Denied?

Most 45385 denials cluster around the screening conversion and the technique documented. The recurring patterns:

Screening and diagnostic misclassification: Billing a screening code after a polyp was removed, or failing to convert to 45385, is a leading colonoscopy denial. Fix it by upgrading to the therapeutic code the moment a polyp is snared.

Missing or crossed screening modifier: Omitting PT, or using PT on commercial and 33 on Medicare, denies the claim and can wrongly bill the patient. Fix it by matching PT to Medicare and 33 to commercial.

Undercoding an EMR as 45385: Billing 45385 for an endoscopic mucosal resection understates the work and loses revenue. Fix it by using 45390 when the note documents a lift-and-cut resection.

Unbundled biopsy at the same site: Reporting 45380 with 45385 at the same lesion triggers a bundling edit. Fix it by billing 45380 separately only for a distinct site with modifier 59 or XS.

Retired diagnosis code: Submitting the old Z86.010 for history of polyps now rejects. Fix it by using the expanded 2026 codes such as Z86.0100 or Z86.0101.

Weak documentation: A note that says only “polyp removed” without the technique fails to support 45385. Fix it by documenting cold or hot snare, site, and size.

Consider the classic conversion. A 66-year-old Medicare patient comes in for a routine average-risk screening colonoscopy scheduled as G0121, expecting to owe nothing. The endoscopist finds and snares a 7 mm sigmoid polyp. The correct claim is 45385 with modifier PT. Coded that way, the deductible is waived and the patient owes only the phased-down 15% coinsurance for 2026. Drop the PT modifier and the same claim processes as a standard therapeutic colonoscopy: the full deductible and 20% coinsurance apply, and the patient gets a bill for a screening they were told was free. The physician fee is only about $290, but the patient-satisfaction damage and the appeal work cost far more. One modifier is the whole difference.

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