Why Are Payers Denying Biopsy and Polypectomy on the Same Colonoscopy?
As of 2026, payer denials on colonoscopy claims that bill both CPT 45380 (colonoscopy with biopsy) and CPT 45385 (colonoscopy with snare polypectomy) in the same session are one of the most common and costly denial patterns in gastroenterology billing. NCCI bundling edits treat these codes as a column 1/column 2 pair, meaning the biopsy code is bundled into the polypectomy code unless the two procedures were performed on clinically distinct lesions at separate anatomic sites, documented clearly in the operative note.
The bundling rule: When a biopsy and a snare polypectomy are performed on the same lesion during the same colonoscopy, only the higher-value code (45385) is billable. The biopsy is considered part of the polypectomy and cannot be reported separately.
When both codes are separately billable: When the biopsy and polypectomy involve different lesions at different anatomic sites, both codes can be reported with modifier 59 (or XS for Medicare) appended to the lesser code, supported by documentation that clearly identifies each lesion and its location.
The denial code to watch: CO-97 (“the benefit for this service is included in the payment/allowance for another service already adjudicated”) is the adjustment reason code most commonly returned on these denials. It signals a bundling edit, not a coverage exclusion.
The NCCI Edit Behind the Denial
The National Correct Coding Initiative (NCCI) maintains procedure-to-procedure (PTP) edit pairs that define which codes cannot be billed separately unless specific conditions are met. CPT 45380 and CPT 45385 are an NCCI edit pair. In this pairing, 45385 (polypectomy by snare) is the column 1 code, and 45380 (biopsy) is the column 2 code. The edit carries a modifier indicator of 1, which means the bundling can be overridden with an appropriate modifier when the clinical circumstances support it.
The logic is straightforward: a snare polypectomy inherently involves visualization and tissue removal. When a biopsy is taken from the same lesion that is then snare-removed, the payer treats the biopsy as part of the polypectomy, not a separate procedure. Billing both for the same lesion is unbundling, and payers deny it automatically through their edit systems.
The problem GI practices run into is that the edit fires on every same-session claim where 45380 and 45385 appear together, regardless of whether the procedures were on the same lesion or different lesions. The payer’s system does not read the operative note. It reads the code pair, and if no modifier is present, the claim denies. For a full overview of how NCCI edits affect GI procedure billing, see our guide on NCCI bundling edits for GI procedures.
When Can You Bill 45380 and 45385 Together?
Both codes are separately reportable in one clinical scenario: the biopsy and the polypectomy were performed on different lesions at different anatomic sites during the same colonoscopy. The operative note must identify each lesion individually, describe its location (ascending colon, sigmoid colon, cecum, etc.), and document the specific technique used on each. A biopsy of a suspicious area in the ascending colon and a snare polypectomy of a polyp in the sigmoid, for example, is a separately billable pair.
When this scenario is present, the practice appends modifier 59 (Distinct Procedural Service) or, for Medicare claims, modifier XS (Separate Structure) to the column 2 code (45380). The modifier tells the payer that the biopsy was not part of the polypectomy and was performed at a clinically distinct site.
One question we hear constantly from GI practice managers is why their modifier 59 claims still deny. Across the billing companies we vet, the answer is almost always documentation, not the modifier itself. The modifier signals that the procedures are distinct, but the operative note has to prove it. If the note says “biopsy and polypectomy were performed during colonoscopy” without specifying separate lesions and separate locations, the payer has no basis to release the bundle, even with the modifier attached.
Same Lesion vs. Different Lesion Billing
This is the decision point the entire denial hinges on, and it must be resolved before the claim is submitted.
| Scenario | What to Bill | Modifier Needed | Expected Outcome |
| Biopsy and snare polypectomy on the SAME lesion | 45385 only | None | Paid at full allowable for 45385 |
| Biopsy on lesion A (ascending colon), snare polypectomy on lesion B (sigmoid) | 45385 + 45380 | 59 or XS on 45380 | Both paid if documentation supports distinct sites |
| Biopsy only, no polypectomy performed | 45380 only | None | Paid at full allowable for 45380 |
| Snare polypectomy only, no separate biopsy | 45385 only | None | Paid at full allowable for 45385 |
| Both submitted without modifier on different-lesion scenario | 45385 + 45380 | Missing | 45380 denied (CO-97) |
The table above is the reference your coding team should use before every same-session colonoscopy claim that involves both a biopsy and a polypectomy. If the operative note does not clearly establish two separate lesions at two separate sites, only the higher-value code should be billed.
Same-session colonoscopy denials on biopsy and polypectomy pairs are one of the highest-volume, highest-dollar denial patterns in GI billing. If your team is losing revenue to CO-97 bundling edits, missing modifier 59 on legitimate claims, or spending hours on appeals that should not have been needed in the first place, a billing partner with GI-specific coding expertise catches these issues before submission. Get matched with vetted gastroenterology billing companies, free.
How to Appeal a CO-97 Colonoscopy Bundling Denial
The biggest issues we see providers run into with these denials are appeals that restate the claim without adding anything the payer did not already have. A successful appeal on a CO-97 bundling denial requires clinical evidence that the bundling edit was misapplied to the specific encounter. Here is what the appeal must include.
Submit the full operative note. The note must name each lesion individually, state the anatomic location of each, describe the technique used on each (cold forceps biopsy vs. snare polypectomy), and document the findings separately.
Identify the distinct sites explicitly in the appeal letter. Write “Lesion 1 was located in the ascending colon and was biopsied using cold forceps (45380). Lesion 2 was located in the sigmoid colon and was removed by snare polypectomy (45385). These are clinically distinct lesions at separate anatomic sites.”
Reference the NCCI modifier indicator. The PTP edit for 45380/45385 carries a modifier indicator of 1, which means the bundling is overridable when the procedures are distinct. Cite this in the appeal.
Include the pathology report. Pathology results from two different specimens at two different sites are the strongest evidence that two distinct procedures occurred. If the pathology report references two separate specimen containers from two separate locations, include it.
Attach modifier 59 or XS if it was missing on the original claim. If the original submission lacked the modifier and the documentation supports distinct sites, resubmit with the modifier as a corrected claim (if within timely filing) or include it with the appeal.
Do not bill the patient for a CO-97 denial. A CO-97 is a contractual obligation adjustment. The denied amount is a billing dispute between the practice and the payer, not a patient responsibility. Billing the patient for a bundled denial creates compliance exposure.
Why This Denial Pattern Is Increasing in 2026
Providers often come to us after a quarter of rising denial rates on colonoscopy claims with no obvious coding change on their end. In our experience matching providers with billing partners, the increase traces to two converging factors. First, commercial payers are tightening their automated edit systems to flag any same-session claim with multiple colonoscopy technique codes, regardless of clinical context. Second, the BCBS multi-procedure reimbursement changes that took effect in September 2026 expanded the scope of bundling logic applied to GI endoscopy across multiple state affiliates.
UnitedHealthcare, Aetna, and several regional Blues plans have all updated their claims processing systems in 2026 to apply NCCI-style bundling edits more aggressively on endoscopy claims. These edits fire automatically and do not review the operative note before denying. The result is a surge in denials on claims that are clinically legitimate but were submitted without the modifier or without documentation clear enough to survive an automated review.
For practices billing in ambulatory surgery center settings, the denial compounds because the facility and professional components deny independently, doubling the appeal workload. See our analysis of how the 2026 site-of-service reimbursement shift affects GI endoscopy for the broader payment context.
Preventing the Denial Before Submission
The most cost-effective response to this denial trend is not a better appeal workflow. It is a pre-submission workflow that catches the bundling issue before the claim goes out. These are the steps that eliminate the denial at the source.
Build a pre-submission edit check for 45380 and 45385 on the same claim. Most practice management systems and clearinghouses can flag NCCI edit pairs before transmission. If your system is not catching 45380/45385 same-session claims before they leave, configure it.
Require the operative note to name each lesion and its location before the coder selects codes. A note that says “multiple biopsies and polypectomy performed” without site-specific detail will lose the appeal every time. Structured templates that prompt the endoscopist to document each lesion individually prevent this gap.
Apply modifier 59 or XS only when the documentation supports distinct sites. Appending the modifier reflexively without verifying the operative note is the fastest path to a modifier audit. The modifier is a clinical assertion, not a denial override switch.
Match the pathology order to the coding. If the coder bills two separate procedures, the pathology report should show two separate specimens from two separate locations. A single-specimen pathology report contradicts a two-code claim.
Track denial rates by payer on this specific code pair. Not all payers apply the same edit logic. Knowing which payers auto-deny 45380/45385 and which require documentation review before release lets the billing team adjust its workflow by payer rather than treating every claim the same way.
For the broader picture of how colonoscopy coding affects GI reimbursement under the 2027 Medicare fee schedule, see 2027 Medicare GI payment changes.
Frequently Asked Questions
Can you bill 45380 and 45385 together on the same colonoscopy?
Yes, but only when the biopsy (45380) and the snare polypectomy (45385) were performed on different lesions at different anatomic sites during the same session. The column 2 code (45380) must carry modifier 59 or XS, and the operative note must clearly document both lesions and their locations separately.
What does denial code CO-97 mean on a colonoscopy claim?
CO-97 means “the benefit for this service is included in the payment/allowance for another service already adjudicated.” On a colonoscopy claim, it signals that the payer’s edit system bundled the biopsy into the polypectomy because the two codes are an NCCI edit pair. It is a contractual adjustment, not a patient responsibility.
What is the difference between modifier 59 and modifier XS?
Both modifiers indicate a distinct procedural service. Modifier 59 is the general NCCI-associated modifier accepted by most payers. Modifier XS (Separate Structure) is a more specific subset modifier preferred by Medicare that identifies a procedure performed on a separate organ or anatomic structure. For colonoscopy bundling appeals, either communicates the same clinical fact.
Can I bill the patient if a CO-97 denial is not overturned?
No. CO-97 is a contractual obligation (CO group code) adjustment. That means the denied amount is the practice’s write-off under the payer contract, not a balance that can be shifted to the patient. Billing a patient for a CO-97 denial creates compliance risk and may violate the provider agreement.
What documentation supports a successful appeal?
The appeal must include the full operative note naming each lesion and its anatomic location, the technique used on each, modifier 59 or XS on the column 2 code, and ideally the pathology report showing two separate specimens from two separate sites. Cite the NCCI modifier indicator of 1 on the 45380/45385 edit pair to show the bundle is overridable.
Why is my modifier 59 claim still being denied?
The most common cause is documentation that does not clearly establish two distinct lesions at two separate anatomic sites. The modifier tells the payer the procedures are distinct, but the operative note must prove it. If the note blends the two procedures into a single narrative without site-specific detail, the payer has no basis to release the bundle.
Does the multiple endoscopy payment reduction apply to this scenario?
Yes. When both codes are separately payable, the multiple endoscopy payment reduction reduces the lower-valued code. The higher-valued code (typically 45385) pays at full allowable, and the second code is reduced because the diagnostic colonoscopy component (45378) is already included in the base payment of the first code.
Next Steps
Need the full NCCI bundling framework for GI? Read our guide on NCCI bundling edits for GI procedures.
Billing colonoscopy with EMR? See our coding guide for CPT code 45390.
Navigating screening vs. diagnostic colonoscopy rules? Start with our guide on ICD-10 code Z12.11 for colon cancer screening.
Ready to stop losing revenue to preventable bundling denials? Get matched with a GI billing partner who catches these issues before claims go out.
Every colonoscopy session that involves both a biopsy and a polypectomy carries denial risk if the coding and documentation workflow is not built to handle it. Gastroenterology Billing connects GI practices and endoscopy centers across all 50 states with billing companies that know the NCCI edit pairs, the modifier rules, and the appeal process from the inside. Over 2,000 providers matched, more than 15 years in medical billing, rates starting as low as 2.95%, and 100% free for providers.
