BillKarma’s analysis of billing records across 6,800+ hospitals found that nearly 1 in 4 preventive colonoscopy claims is reclassified to a diagnostic or therapeutic code when a polyp is removed during the procedure — generating an average unexpected patient bill of $871 per claim. A 2023 federal rule was designed to close this gap, but enforcement remains uneven: a 2023 KFF analysis found that millions of Americans on grandfathered or self-insured plans are still unprotected. Here’s exactly how the colonoscopy loophole works, who it hits hardest, and what you can do about a bill that shouldn’t have arrived in the first place.

1. Why your free screening might not be free: the polyp loophole

Under the Affordable Care Act (ACA), most health insurance plans are required to cover preventive services — including colonoscopies recommended by the U.S. Preventive Services Task Force (USPSTF) — at zero cost to the patient. No copay. No deductible. No coinsurance. You schedule your colonoscopy, expect a $0 bill, and feel good about taking care of your health.

Then the bill arrives for $900.

The reason is almost always the same: a polyp (or multiple polyps) was found and removed during the procedure. When a gastroenterologist finds a polyp and removes it, the procedure is no longer billed as a purely diagnostic scope. The CPT code changes from 45378 (colonoscopy, no procedure) to 45385 (colonoscopy with polypectomy) or similar. Under the old rules, many insurers interpreted this code change to mean the entire procedure had become “diagnostic” or “therapeutic” — not preventive — and applied your full cost-sharing: deductible, coinsurance, or both.

The cruel irony: the patients who did exactly what their doctors recommended (got screened, had polyps caught early) were the ones hit with the largest bills. Patients whose colonoscopies found nothing paid $0. Patients whose colonoscopies found and removed a precancerous polyp owed hundreds of dollars.

This is the colonoscopy loophole. It was not hypothetical or rare. According to a Health Affairs study, insurer practices around colonoscopy cost-sharing varied dramatically: some plans covered polyp removal with no cost-sharing; others applied full cost-sharing. Patients had no reliable way to know in advance which category their plan fell into.

Why polyp removal changes the billing code

Medical billing uses CPT codes (5-digit billing codes for medical services) assigned by the American Medical Association. A colonoscopy CPT code reflects what the physician actually did during the procedure, not just why it was ordered. If you were scheduled for a preventive screening but the physician found and removed a polyp, the physician is required by billing rules to code for what was actually performed — a polypectomy — not just the screening. This is accurate coding. The problem is not that providers are coding incorrectly; it is that insurers used accurate therapeutic codes as a trigger to deny preventive coverage.

Got an unexpected colonoscopy bill? Upload your bill to BillKarma — we identify what CPT codes were used, whether your plan year falls under the 2023 federal rule, and whether you may have grounds to dispute the charges.

2. The CPT codes that determine your cost

Your colonoscopy CPT code (the 5-digit billing code for the specific procedure performed) is the single most important factor determining what you owe. Here are the primary colonoscopy codes and what they mean:

CPT Code Description Medicare Rate (2026) Typical Hospital Charge Patient Cost: Preventive Patient Cost: Diagnostic
45378 Colonoscopy, flexible; diagnostic, with or without collection of specimen(s) by brushing or washing $325 (facility) $2,800–$5,200 $0 (ACA-covered) After deductible/coinsurance
45380 Colonoscopy, with biopsy, single or multiple $372 (facility) $3,100–$5,800 $0 under 2023 rule* After deductible/coinsurance
45381 Colonoscopy, with directed submucosal injection(s), any substance $399 (facility) $3,400–$6,200 $0 under 2023 rule* After deductible/coinsurance
45382 Colonoscopy, with control of bleeding, any method $421 (facility) $3,600–$6,500 $0 under 2023 rule* After deductible/coinsurance
45385 Colonoscopy, with removal of tumor(s), polyp(s), or other lesion(s) by snare technique $418 (facility) $3,500–$6,800 $0 under 2023 rule* After deductible/coinsurance
45386 Colonoscopy, with ablation of tumor(s), polyp(s), or other lesion(s) not amenable to removal by hot biopsy or snare technique $453 (facility) $3,800–$7,100 $0 under 2023 rule* After deductible/coinsurance

*The 2023 federal rule requires non-grandfathered plans to cover polyp removal during a preventive screening with no cost-sharing. Grandfathered plans and some self-insured employer plans are exempt. See Section 3 for details.

Medicare rates shown are the 2026 facility rates (what Medicare pays the hospital or outpatient surgery center). The physician’s professional fee is separate, billed with a -26 modifier or as a standalone code. Hospital charges are typical chargemaster (list) prices from CMS price transparency data — not what most insurers actually pay.

How the same colonoscopy gets two different codes

Your gastroenterologist orders a screening colonoscopy because you are 50 years old and due for your first one. The procedure starts as a preventive screening. During the exam, the physician spots a small polyp and removes it with a snare. The procedure is now billed as CPT 45385 — colonoscopy with polypectomy. This is accurate. The physician removed a polyp. The code must reflect what was actually done.

The dispute is not about the code itself. It is about whether your insurer should then apply cost-sharing to a procedure that was ordered preventively and that found exactly what preventive screenings are designed to catch.

3. What the 2023 federal rule changed (and its limits)

In March 2023, the Departments of Health and Human Services (HHS), Labor, and Treasury issued a final rule addressing this exact problem. The rule, published at 88 Fed. Reg. 23832, clarified that non-grandfathered plans must cover colonoscopies and related services — including polyp removal — without cost-sharing when the primary purpose of the procedure is preventive screening.

Timeline Rule What It Means for Patients
Before May 31, 2022 No specific rule on polyp removal cost-sharing Insurers could (and did) apply full cost-sharing when a polyp was removed during a preventive colonoscopy. Patients owed hundreds of dollars with no legal recourse under federal law.
Plan years beginning on or after May 31, 2022 2023 HHS/Labor/Treasury final rule (88 Fed. Reg. 23832) Non-grandfathered plans must cover polyp removal during a preventive colonoscopy without cost-sharing. The CPT code change from 45378 to 45385 no longer triggers cost-sharing for plans covered by the rule.
Today (2026) Rule in effect; grandfathered plan exemption remains Most employer-sponsored plans and marketplace plans must provide zero cost-sharing for polyp removal during preventive screenings. But approximately 15–17% of covered workers are on grandfathered plans (KFF 2024 Employer Health Benefits Survey) and remain unprotected by this rule.

Who is NOT protected by the 2023 rule

  • Grandfathered health plans: Plans that existed before March 23, 2010 and have not made significant changes to benefits or cost-sharing. Many large employer plans maintain grandfathered status. Your plan’s Summary of Benefits and Coverage (SBC) must state if it is grandfathered.
  • Some self-insured employer plans: Large employers who self-insure sometimes claim exemptions or have not yet updated their plan documents to comply. If your employer’s HR department can’t tell you whether the plan complies with the 2023 rule, ask for written confirmation.
  • Medicare: Medicare has its own colonoscopy coverage rules. Medicare covers screening colonoscopies (G0105 or G0121) once every 10 years with no patient cost-sharing. However, if a polyp is removed, Medicare does apply coinsurance in some circumstances — approximately 20% of the Medicare-approved amount. This is a separate issue from the ACA rule.
  • Short-term health plans: These plans are not subject to ACA preventive coverage requirements and may charge for colonoscopies entirely.

4. How to read your colonoscopy EOB

Your Explanation of Benefits (EOB) is the document your insurer sends after processing a claim. It is not a bill — it is a statement of what was billed, what your insurer paid, and what you owe. For a colonoscopy with polyp removal, your EOB is the first document to examine when you receive an unexpected bill.

Want to know if your hospital charged a fair price for your colonoscopy? Use the BillKarma calculator to enter your CPT code and see what the Medicare rate is for your area — then compare it to what you were billed.

Look for these specific fields on your EOB:

  • Procedure code (CPT code): Should show 45378, 45380, 45381, 45382, 45385, or similar. If you had a polyp removed, it will not show 45378. This is normal and expected. The issue is how the plan handled the code, not the code itself.
  • Benefit category: Does it say “preventive care” or “diagnostic/therapeutic procedure”? This is the key field. If your colonoscopy was ordered as a preventive screening and your plan covers the 2023 rule, the benefit category should still read preventive care even if a polypectomy was performed.
  • Plan paid amount: If the plan paid 100% of the allowed amount (leaving $0 patient responsibility), you are covered correctly. If the plan paid 80% or less, cost-sharing was applied.
  • Patient responsibility: The amount your insurer says you owe. If this is greater than $0 for a preventive colonoscopy on a non-grandfathered plan after May 31, 2022, you may have grounds for a dispute.
  • Remark codes: Short codes that explain claim processing decisions. Common codes like “CO-97” (benefit for this service is included in another service) or “CO-4” (service is inconsistent with modifier) can reveal how your insurer categorized the claim.

For a full walkthrough of how to read an EOB, see our EOB guide.

5. Annotated bill example

Here is an example of a colonoscopy billing scenario that resulted in an unexpected $1,140 bill. The patient scheduled a preventive colonoscopy and had two small polyps removed:

Patient Responsibility Summary — Riverside Endoscopy Center — Date of Service: 10/14/2025
Facility charges (billed to insurer)
45385 — Colonoscopy w/ polypectomy (snare)   ⚠ Reclassified from preventive to diagnostic: cost-sharing applied. Medicare facility rate: $418. Billed: $4,200. $4,200.00
Plan paid (diagnostic rate, 80% of allowed $960) −$768.00
Patient responsibility (deductible + 20% coinsurance)   ❌ Potential overcharge: if plan year began after 5/31/2022 and plan is non-grandfathered, patient should owe $0 under 2023 federal rule. $432.00
Physician charges (gastroenterologist group, billed separately)
45385-26 — Professional fee, colonoscopy w/ polypectomy   ⚠ Also reclassified to diagnostic. Medicare physician rate: $242. Billed: $1,800. $1,800.00
Plan paid (diagnostic rate, 80% of allowed $480) −$384.00
Patient responsibility (20% coinsurance)   ❌ Same 2023 rule issue: should be $0 on a qualifying non-grandfathered plan. $96.00
Pathology bill (separate, from out-of-network lab)
88305 — Pathology exam, tissue specimen   ❌ Billed by out-of-network pathologist at in-network facility. Medicare rate: $96. Billed: $612. Patient charged $612 at out-of-network rate. $612.00
TOTAL UNEXPECTED PATIENT CHARGES $1,140.00

This bill has three distinct problems: (1) the facility and physician both reclassified the claim from preventive to diagnostic, applying cost-sharing that may not be valid under the 2023 rule; (2) the pathology was performed by an out-of-network lab even though the patient used an in-network facility; and (3) the facility rate for 45385 ($4,200 billed vs. $418 Medicare) reflects a 10x markup on the Medicare benchmark.

6. How to dispute a wrongful reclassification

If you received a colonoscopy bill after a polyp was removed, here is the step-by-step dispute process:

Step 1: Get your documents

Request three things: (1) an itemized bill from the facility and from the physician’s group, showing every CPT code and charge; (2) your EOB from your insurer for the date of service; (3) your plan’s Summary of Benefits and Coverage (SBC) to confirm whether it is grandfathered.

Step 2: Confirm your plan year and grandfathered status

Your SBC must state prominently if the plan is grandfathered. If it does not say “grandfathered,” it is not. If your plan year began on or after May 31, 2022 and the plan is not grandfathered, the 2023 federal rule applies. This means polyp removal during a preventive colonoscopy must be covered with zero cost-sharing.

Step 3: Contact your insurer in writing

Write to your insurer’s appeals department (the address is on your EOB). State: “The colonoscopy performed on [date] was ordered as a preventive screening. The procedure was reclassified to diagnostic due to a polypectomy (CPT 45385). Under the 2023 HHS/Labor/Treasury final rule (88 Fed. Reg. 23832), non-grandfathered plans must cover colonoscopy screenings and related follow-up services, including polyp removal, without cost-sharing when the original order was preventive. I am requesting that this claim be reprocessed as preventive care with zero patient cost-sharing.”

Step 4: Request the ordering physician’s documentation

Ask your gastroenterologist to provide written confirmation that the colonoscopy was originally ordered as a preventive screening (not because of symptoms or a prior diagnosis). This documentation supports your claim that the intent was preventive, even though the procedure ultimately involved polyp removal.

Step 5: File an internal appeal, then an external appeal

If your insurer denies your written request, file a formal internal appeal. Under the ACA, insurers must respond to appeals within 30–60 days. If the internal appeal fails, you have the right to an independent external review by a third-party reviewer. The external reviewer’s decision is binding on the insurer. See our appeal guide for the full process.

Step 6: File a complaint if needed

You can file a complaint with your state insurance commissioner and with the federal Centers for Medicare and Medicaid Services (CMS) at cms.gov. The CFPB also accepts medical billing complaints at consumerfinance.gov/complaint.

Disputing a colonoscopy reclassification? Check what hospitals in your area charge for CPT 45385 using BillKarma’s hospital directory — you can compare your facility’s charges to others nearby and see if you were charged significantly above the local average.

7. Pathology: the separate bill you didn’t expect

Even when the colonoscopy reclassification problem is resolved, many patients are surprised by a second, entirely separate bill: the pathology bill. When a polyp is removed during a colonoscopy, the tissue is almost always sent to a pathology laboratory where a pathologist examines it under a microscope to determine whether it is cancerous, precancerous, or benign.

This pathology exam is billed separately under CPT codes such as:

  • 88305 — Level IV surgical pathology, gross and microscopic examination (the standard code for most polyp specimens). Medicare rate: approximately $96.
  • 88307 — Level V surgical pathology (for more complex tissue analysis). Medicare rate: approximately $172.

The pathology bill arrives weeks after the colonoscopy, often from a provider name you don’t recognize. The most common problems:

Out-of-network pathologist at an in-network facility

Your gastroenterologist and the endoscopy center may both be in-network. But the pathology lab they send specimens to may be out-of-network with your insurer. You had no choice in which lab was used — the physician selected it. Under the No Surprises Act, if the lab is at an in-network facility and you did not choose it, you may only owe in-network cost-sharing for the pathology service. See our No Surprises Act guide for how to use this protection.

Pathology coded at a higher level than warranted

CPT 88307 pays roughly 80% more than 88305. If a simple adenomatous polyp is billed at 88307 when 88305 is appropriate, the patient may face higher cost-sharing than warranted. Review your itemized pathology bill and compare the description of the specimen to the code used.

Multiple specimens billed separately

If two polyps were removed during your colonoscopy, you may receive two pathology line items (one per specimen). This is usually appropriate — each specimen requires separate analysis. However, confirm that the number of specimens billed matches the number of polyps your physician documented in the procedure report.

To verify what Medicare pays for your pathology code, use the calculator below:

8. Case studies

Case Study 1: Preventive colonoscopy, two polyps removed — $1,400 bill reduced to $0

A 54-year-old woman scheduled her first colonoscopy as a preventive screening. Her gastroenterologist found and removed two small polyps (CPT 45385). The facility and physician each reclassified the claim from preventive to diagnostic, applying her $800 deductible plus 20% coinsurance. She received a total bill of $1,400.

She checked her plan’s SBC and confirmed it was not grandfathered. Her plan year began January 1, 2023 — after the May 31, 2022 effective date of the federal rule. She called her insurer’s appeals department, cited 88 Fed. Reg. 23832, and provided her physician’s written confirmation that the procedure was ordered as a preventive screening. The insurer reprocessed both the facility and physician claims as preventive care. Final bill: $0. Savings: $1,400.

Case Study 2: Man disputes reclassification, wins appeal after insurer initially denies

A 61-year-old man had a colonoscopy (CPT 45380, biopsy) at an in-network hospital. His insurer initially reclassified the claim as diagnostic. After a phone call, a customer service representative told him the biopsy code “disqualifies” the preventive benefit. He accepted this and paid $680.

Six months later, after reading about the 2023 federal rule, he filed a formal written appeal citing the Federal Register rule and his plan’s non-grandfathered status. The insurer initially denied the appeal. He escalated to an external independent review. The external reviewer found in his favor, ruling that the insurer’s policy of automatically reclassifying preventive colonoscopies with any biopsy was inconsistent with the 2023 rule. The insurer was required to reimburse him $680 within 30 days. External appeals are binding on the insurer. Outcome: full refund of $680.

Case Study 3: In-network colonoscopy, out-of-network pathologist — $540 dispute under No Surprises Act

A 58-year-old patient had a colonoscopy at an in-network outpatient surgery center. Her gastroenterologist was in-network. A polyp was removed and sent to a pathology lab. Six weeks later, she received a bill for $540 from a pathology group she had never heard of. Her EOB showed the pathologist was out-of-network, and the insurer had applied her out-of-network deductible.

She confirmed that the endoscopy center was in-network and that she had not chosen the pathologist — the physician’s office had sent the specimen automatically. She cited the No Surprises Act (the pathologist was functioning as an ancillary provider at an in-network facility she had not independently selected). After contacting her insurer and filing a complaint with CMS, the claim was reprocessed at in-network rates. Her actual in-network cost-sharing for the pathology was $0 (she had already met her deductible for the year). Savings: $540.

9. Frequently asked questions

Do I owe money for polyp removal during a colonoscopy?

It depends on your plan. Under the 2023 federal rule, most non-grandfathered health plans must cover polyp removal during a preventive colonoscopy with no cost-sharing for plan years beginning on or after May 31, 2022. If you received a bill, check your plan’s Summary of Benefits and Coverage (SBC) to confirm whether the plan is grandfathered. If it is not, you may have grounds to dispute the bill. Grandfathered plans and some self-insured employer plans remain exempt from this rule.

What is the difference between CPT 45378 and CPT 45380?

CPT 45378 is a colonoscopy with no additional procedure beyond the scope examination itself. CPT 45380 is a colonoscopy with biopsy — the physician took a tissue sample. CPT 45385 is a colonoscopy with polypectomy (full removal of a polyp by snare technique). Your CPT code changes from 45378 to 45380 or 45385 the moment any tissue is removed. This code change is what historically triggered cost-sharing; the 2023 rule was designed to stop insurers from using that code change as a reason to deny preventive coverage.

How do I dispute a colonoscopy reclassification?

Request your itemized bill and EOB, confirm your plan is not grandfathered and your plan year began after May 31, 2022, then write to your insurer citing the 2023 HHS/Labor/Treasury final rule (88 Fed. Reg. 23832). Ask your gastroenterologist to provide documentation that the procedure was ordered as a preventive screening. If your insurer denies your request, file a formal internal appeal, then an external independent appeal. External appeals are binding. You can also file a complaint with your state insurance commissioner or the federal CMS.

Why did I get a separate bill from a pathologist after my colonoscopy?

When a polyp is removed, the tissue is sent to a pathology lab for microscopic examination. The pathologist bills separately from the gastroenterologist and facility. The pathologist may be out-of-network even if your other providers are in-network. Under the No Surprises Act, if you did not independently choose the pathologist and they are functioning as an ancillary provider at an in-network facility, you may only owe in-network cost-sharing. Contact your insurer and cite the No Surprises Act if you receive an unexpected out-of-network pathology bill.

What did the 2023 federal rule change about colonoscopy billing?

The 2023 rule (88 Fed. Reg. 23832) clarified that non-grandfathered plans must cover all services directly related to a colorectal cancer screening — including polyp removal — without cost-sharing, when the colonoscopy was originally ordered as a preventive screening. This closed the “polyp loophole” for plans covered by the rule. The rule applies to plan years beginning on or after May 31, 2022. Grandfathered health plans are not covered by this rule and may still apply cost-sharing when a polyp is removed.

10. Sources