Gastroenterology Billing Services
If you run a GI practice or an endoscopy center, the hard part of the billing is not any single code. One twenty-minute procedure can generate four separate claims from four separate parties — the gastroenterologist's professional fee, the surgery center's or hospital outpatient department's facility fee, the pathologist's per-jar specimen billing, and, where the case ran under monitored anesthesia rather than the endoscopist's own sedation, the anesthesia provider's claim — and those four have to agree with each other. When they disagree, because the procedure note says three polyps and pathology bills two jars, or moderate sedation is billed on a case an anesthetist also filed for, the payer sees the disagreement before the practice does.
Over the top of the code families sit two rules that decide the money, and both are routinely misread. Same-family endoscopies in one session are paid under a special Medicare rule rather than the ordinary multiple-surgery reduction, so a correct payment can look like an underpayment and get appealed. And a screening colonoscopy that converts intra-procedure keeps its screening status only if the claim says so — with a different flag on a Medicare claim than on a commercial one, and the cost of getting it wrong landing on a patient's bill rather than the practice's.
We work the whole encounter rather than one claim inside it. We reconcile specimen counts to the pathology units before submission, keep the sedation and anesthesia claims from overlapping, sequence same-session interventions to the sites the note documents, verify each patient's benefit instead of quoting a figure, and re-check apparent underpayments against the endoscopy rule before an appeal goes out. Built for high-volume endoscopy practices, the surgery centers they operate in, and infusion programs where prior authorization sets the schedule.
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What Is Gastroenterology Billing?
Gastroenterology billing is the work of making one procedure's several claims agree — the endoscopist's, the facility's, the pathologist's and, where monitored anesthesia was used, the anesthesia provider's — and applying the two rules that decide what is paid. The first is the endoscopy payment rule. Same-family endoscopies in one session are not paid under the ordinary multiple-surgery reduction: Medicare pays the full value of the highest-valued study plus the difference between the next highest and the base, because each intervention already contains the diagnostic study (Medicare Claims Processing Manual, chapter 12, section 40.6). That is a correct payment, not an underpayment to appeal. The second is conversion. A planned screening colonoscopy that removes tissue in the same encounter is still a colorectal cancer screening test under 42 CFR 410.37, and the claim has to carry the flag that says so — a different one on Medicare than on a commercial plan. On Medicare the deductible does not apply and the coinsurance share is stepping down on a published schedule, so we bill the percentage for the year of service. On a commercial plan, what the patient actually sees depends on plan design and network status, so we verify the benefit rather than promise one.
- 45378 diagnostic vs 45385 polypectomy — different code, different base-endoscopy arithmetic, different patient bill
- Modifier PT on Medicare conversions and modifier 33 on commercial preventive claims are not interchangeable
- Same-session endoscopies paid on the special endoscopy rule, not the ordinary 100/50 multiple-surgery reduction
- Step-therapy documentation packaged before the biologic prior authorization goes out (J1745, J3380)
Who This Page Is For
Common Billing Friction in Gastroenterology
Screening-to-diagnostic conversion, and what the patient actually owes
When a screening colonoscopy finds a polyp and becomes a polypectomy, the encounter does not stop being a screening test. Since 1 January 2022, 42 CFR 410.37(j) has defined colorectal cancer screening tests to include a planned screening colonoscopy that involves the removal of tissue or other matter in the same clinical encounter. Two consequences follow, and they are different from each other. The Part B deductible does not apply: 42 CFR 410.160(b) excludes colorectal cancer screening tests, and a surgical or anesthesia service furnished in connection with and in the same clinical encounter as a planned screening test, from the annual deductible. Coinsurance is being phased out on a schedule, not waived: under 42 CFR 410.152, Medicare pays 85 percent of these converted screening services for calendar years 2023 through 2026, 90 percent for 2027 through 2029 and 100 percent from 1 January 2030 — so the patient's share is 15 percent today, 10 percent from 2027 and nothing from 2030. Any page quoting a flat percentage without the year will be wrong on 1 January 2027. Commercial plans run on a different rule: 45 CFR 147.130 requires group health plans and issuers to cover services rated A or B by the US Preventive Services Task Force without cost sharing, and modifier 33 is the flag that the service was furnished as preventive. Plan design and network status still decide what a specific patient sees, which is why we verify the benefit rather than promise a number.
The endoscopy payment rule is not the multiple-surgery rule
This is the most commonly misstated rule in GI billing, and getting it wrong makes a correct payment look like an underpayment. Ordinary multiple surgery pays 100 percent of the highest valued procedure and 50 percent of the second through fifth. Endoscopies in the same family do not use that. The Medicare Claims Processing Manual, chapter 12, section 40.6, directs payment of the full value of the highest valued endoscopy plus the difference between the next highest endoscopy and the base endoscopy, because the value of each intervention already has the diagnostic study built into it. CMS's worked example is a colonoscopy where the physician biopsies one lesion (45380) and removes a polyp from a different part of the colon (45385): the payment is the full value of 45385 plus the difference between 45380 and 45378. The base endoscopy is published per code in the physician fee schedule relative value file — 45378 for 45380, 45385 and 45390; 43235 for 43239 and 43249 — alongside a multiple procedure indicator of 3, which is what tells the claims system to use this rule. The same arithmetic explains why a diagnostic EGD is not separately billable beside an EGD with biopsy: the biopsy code already contains it. Unbundling genuinely distinct work still needs modifier 59 or the more specific XS, plus documentation of the separate site or lesion.
Sedation: the endoscopist's moderate sedation versus a separately billed anesthesia claim
Endoscopy runs either under moderate sedation administered by the endoscopist, billed on 99152 and 99153 by the same physician performing the procedure, or under monitored anesthesia care from an anesthesiologist or CRNA who files their own claim. The anesthesia codes are specific to the study: 00811 lower GI endoscopy not otherwise specified, 00812 screening colonoscopy, 00813 combined upper and lower, 00731 upper GI endoscopy not otherwise specified, 00732 ERCP. 00810 is a deleted code (AAPC lists it as deleted effective 1 January 2018), so charge masters that still carry it risk rejections. Where an anesthesia provider bills, the endoscopist does not also bill moderate sedation, and plans reconcile the two claims against each other and recoup the duplicate. The defense is procedural rather than clerical: the sedation provider and the level of sedation are named in the procedure note on every case, and the charge is built from the note.
Biologic infusion buy-and-bill, drug waste, and step-therapy authorization
IBD treatment runs through buy-and-bill biologic infusions: J1745 (infliximab, per 10 mg), J3380 (vedolizumab, per 1 mg), and the biosimilar Q-codes Q5103, Q5104 and Q5121, paired with infusion administration codes 96365 for the initial hour and 96366 for each additional hour. These drugs are not priced on the physician fee schedule — they carry a statutory-exclusion status there and are paid under Part B drug pricing — so the unit arithmetic on the claim, not a fee schedule amount, is what determines payment. Drug waste from single-use vials is billable with modifier JW and is quietly dropped when the vial size and the administered dose are not both documented. Commercial plans commonly gate biologics behind step therapy, and the requirements differ plan to plan and change between plan years. We read the specific policy in force and package what it asks for — drug name, dose, duration and clinical response for each conventional therapy tried — before the authorization goes out, rather than after the first denial.
Turning the procedure log into reconciled claims, specimen by specimen
The audit exposure in GI is rarely a single wrong code. It is a drift between four records of the same twenty minutes: the endoscopy report, the pathology requisition, the anesthesia record and the claim. Pathology is the clearest case. 88305 is billed per specimen, so three separately jarred polyps must produce three units and three jars, and a mismatch between the procedure note's specimen count and the billed units is the kind of finding that pulls months of claims at once. We reconcile forward rather than sampling backward: every case on the endoscopy schedule is matched to a coded claim, every claim is matched to its pathology requisition and its sedation record, and anything that does not reconcile is worked as a named case with a date rather than written off as a variance. Surveillance intervals get the same treatment. Specialty-society surveillance guidance and a plan's own coverage policy are two different documents and they do not always agree, so the interval a payer will actually cover is read from that plan's policy and the clinical justification for a shorter interval is documented before the case is scheduled, not after it is denied.
Gastroenterology-Specific Payer Issues We Watch For
Medicare
Issue: A screening colonoscopy that converts to diagnostic needs modifier PT to adjudicate as a screening test. Billed without it, the Part B deductible that 42 CFR 410.160 excludes gets applied and the patient's share jumps from the phased coinsurance to the full diagnostic cost.
Our approach: Modifier PT on every screening-to-diagnostic conversion, with the claim checked after adjudication to confirm it processed under the preventive benefit. We track the coinsurance percentage by year rather than by habit: 15 percent through 2026, 10 percent from 2027, none from 2030.
UnitedHealthcare
Issue: Same-session EGD claims draw bundling edits, and the base study is usually the cause rather than the payer. An EGD with biopsy already contains the diagnostic EGD, so 43235 billed alongside 43239 is a duplicate of work that is already paid inside 43239.
Our approach: We bill the intervention code alone where one study was performed, and where separate anatomic sites genuinely justify unbundling we apply modifier 59 or XS with the site documented in the procedure note. Underpayments are re-checked against the special endoscopy rule before an appeal goes out, because that rule pays less than the ordinary multiple-surgery percentages and the difference is not an error.
Aetna
Issue: Biologic infusions are gated behind prior authorization with step-therapy criteria that differ by plan and change between plan years. An authorization built from last year's criteria is denied on documentation, not on clinical grounds.
Our approach: We pull the plan's current medical policy before assembling the request, and package failed conventional therapy with drug name, dose, duration of use and clinical response for each agent.
Cigna
Issue: Surveillance-interval coverage is set by each plan's own medical policy, which does not always match specialty-society surveillance guidance. A follow-up scheduled on the guideline interval can be denied on the policy interval.
Our approach: We read the plan's current surveillance policy when the follow-up is scheduled rather than when it is denied, and document the clinical justification for a shorter interval in advance.
What We Handle
Colonoscopy and EGD coding (45378, 45380, 45385, 45390, 43235, 43239, 43249)
Diagnostic, biopsy, snare polypectomy and endoscopic mucosal resection coding with the correct base-plus-intervention pairing, and the special endoscopy payment rule applied rather than the ordinary multiple-surgery reduction. EGD with biopsy and balloon dilation under the same-session rules. ERCP 43260 and capsule endoscopy 91110 included.
Screening-to-diagnostic conversion with modifier PT/33 discipline
Modifier PT applied to Medicare screening conversions and modifier 33 to commercial preventive claims, with the current-year Medicare coinsurance percentage checked rather than assumed — it steps down in 2027 and again in 2030. Patient cost-sharing verified against the specific plan before the claim is released.
Biologic infusion buy-and-bill (J1745, J3380, Q5103/Q5104) with drug waste capture
J-code unit billing, 96365/96366 infusion administration time-based add-ons, modifier JW drug waste documentation, and biosimilar Q-code substitution per payer formulary. Step-therapy documentation packaged for prior auth.
Pathology specimen coordination with 88305 unit counts
Procedure-note specimen counts reconciled to 88305 units before submission, because 88305 is billed per specimen and a count that disagrees with the endoscopy report is an audit trigger rather than a rounding difference. Multi-jar specimen documentation reviewed with the pathology group so both claims describe the same case.
ASC versus hospital outpatient site-of-service coding
POS 24 (ASC) versus POS 22 (hospital outpatient) versus POS 19 (off-campus outpatient) selection per actual location, with professional fee and facility fee coordination across the GI's contracted ASC and hospital privileges.
Sedation versus MAC anesthesia split billing
Moderate sedation billed by the endoscopist on 99152 and 99153 versus a separately filed anesthesia claim on 00811, 00812, 00813, 00731 or 00732, coordinated so the two never overlap and trigger recoupment. The sedation provider and level are named in the procedure note on every endoscopic encounter, and the charge is built from the note rather than from the schedule.
GI office E/M and diagnosis sequencing
Office and consult E/M coding (99202-99215) alongside the procedures, with diagnosis sequencing that survives payer edits: Z12.11 first-listed on screening encounters, K21.9 GERD and K50/K51 IBD chronic-care coding, and the screening-to-diagnostic sequence rules that decide whether the preventive benefit adjudicates.
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Key Gastroenterology CPT Codes
| CPT Code | Description | Medicare Amount CY2026 national, non-facility |
|---|---|---|
| 45378 | Diagnostic colonoscopy (facility amount $165) | $378 |
| 45385 | Colonoscopy with snare polypectomy (facility amount $223) | $500 |
| 45380 | Colonoscopy with biopsy (facility amount $178) | $480 |
| 43239 | EGD with biopsy (facility amount $124) | $419 |
| 43249 | EGD with balloon dilation of the esophagus, under 30 mm (facility amount $136) | $1,180 |
| 43260 | ERCP, diagnostic, including specimen collection when performed | $281 |
| 91065 | Breath hydrogen or methane test | $64 |
| J1745 | Infliximab, not biosimilar, 10 mg — paid under Part B drug pricing, not the fee schedule | — |
Amounts are the Medicare national unadjusted non-facility amounts for CY2026, computed from the published CMS relative value file. They are not what a commercial payer pays, and your locality adjustment moves them. A dash means Medicare publishes no amount for that code — because it is non-covered, bundled, or priced outside the fee schedule.
Why General Billing Teams Miss Gastroenterology Issues
General billing staff handle dozens of specialties and rarely develop the depth needed for gastroenterology coding nuances. Here is what gets missed.
Modifier and bundling errors
Specialty-specific modifier rules and CCI edits are frequently overlooked by teams that do not work exclusively in gastroenterology.
Under-coding high-complexity visits
Gastroenterology encounters often qualify for higher-level E/M codes, but generalist billers default to mid-level codes to avoid audit risk.
Missed payer-specific rules
Each payer has unique coverage and documentation requirements for gastroenterology procedures that general teams rarely memorize.
Slow denial turnaround
Without specialty knowledge, appeal letters lack the clinical specificity needed to overturn gastroenterology denials quickly.
“The screening-to-diagnostic colonoscopy conversion is where most GI practices create both revenue and compliance problems. One wrong modifier choice costs you the procedure payment and creates a patient billing dispute.”
MedPrecision Billing Team
GI Procedure Coding Specialist
Transition Plan
Switching billing partners should not disrupt patient care or cash flow. Our transition plan is designed for zero downtime.
Discovery and Specialty Audit
We review your current gastroenterology billing workflows, denial patterns, and payer mix to build a tailored onboarding plan.
System Integration
We connect to your EHR and practice management system, configure specialty-specific code sets, and validate charge capture workflows.
Parallel Billing Period
We run billing in parallel with your current process for 2-4 weeks to verify accuracy before taking over completely.
Full Transition and Reporting
Once validated, we assume full billing responsibility with monthly reporting dashboards and a dedicated account manager.
Gastroenterology Billing Terms
- Screening-to-Diagnostic Conversion
- A colonoscopy begun as a preventive screening that becomes therapeutic when tissue is removed in the same clinical encounter. Under 42 CFR 410.37(j) it remains a colorectal cancer screening test, which is what preserves the patient's cost-sharing protection — modifier PT on Medicare claims is how the claim says so.
- CCI Bundling Edits
- Correct Coding Initiative edits that define which GI procedure codes cannot be billed together. Endoscopy bundling rules are among the most complex in medical billing, particularly for same-session interventions.
- Buy-and-Bill
- A billing model where the practice purchases biologic medications (Remicade, Entyvio), administers them to patients, and bills the payer for both the drug cost (J-code) and the infusion administration. Requires careful drug waste documentation and inventory management.
- Modifier PT
- Colorectal cancer screening test converted to diagnostic — appended to the converted procedure so the claim adjudicates under the screening benefit. On Medicare that means no Part B deductible and the phased coinsurance share for the year of service, not a blanket zero.
- Endoscopy Base Code
- The diagnostic study whose value is built into every intervention code in the same endoscopy family — 45378 for colonoscopy, 43235 for EGD — and which the fee schedule names per code. It is why 45380 and 45385 are standalone codes rather than add-ons, and why same-session endoscopies are paid as the full value of the highest study plus the difference between the next highest and the base.
- Drug Waste Documentation
- Required documentation of unused biologic medication from single-use vials. Medicare and most commercial payers reimburse for documented drug waste using modifier JW, which can represent significant revenue for infusion practices.
Last updated: 2026-10-02
Common Questions
Common questions about gastroenterology billing services.
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Request ReviewHow do you handle billing when a screening colonoscopy finds and removes polyps?
We code the procedure as a colonoscopy with polypectomy using the appropriate technique-specific code (snare, hot biopsy, etc.) and apply modifier PT to indicate it began as a screening procedure. This preserves the patient's preventive screening benefit while capturing the interventional component.
Can you bill for multiple endoscopic procedures in the same session?
Yes, when properly documented and coded. We apply modifier 59 or XS to distinguish separate procedures and follow CCI bundling edits to ensure each intervention is billable. For example, a colonoscopy with both polypectomy and biopsy at different sites can be billed separately.
How do you manage biologic infusion billing for GI practices?
We handle the complete buy-and-bill cycle including drug J-code billing (J1745 for Remicade, J3380 for Entyvio), infusion administration codes with time-based add-ons, drug waste documentation, and prior authorization for continued therapy.
What is the difference between CPT 45378 and 45385?
45378 is a diagnostic colonoscopy with no intervention; 45380 adds a biopsy; 45385 is a snare polypectomy. They are not add-on codes — each one already contains the value of the diagnostic study, which is why Medicare pays same-session endoscopies on the special endoscopy rule rather than the ordinary multiple-procedure reduction. Medicare's own screening codes are G0105 for a patient at high risk for colorectal cancer and G0121 for one who is not. When a screening converts intra-procedure, bill the code for the procedure actually performed and append modifier PT for Medicare or modifier 33 for a commercial preventive claim.
How do you bill a screening colonoscopy that becomes diagnostic?
Code the procedure actually performed — 45385 if a polyp was removed by snare — keep the screening indication as the primary diagnosis, and append modifier PT for Medicare or modifier 33 for commercial payers. The modifier is how the claim says the encounter began as a screening, which matters because 42 CFR 410.37 treats a planned screening colonoscopy that removes tissue in the same encounter as still a colorectal cancer screening test. On Medicare that means no Part B deductible (42 CFR 410.160) and a coinsurance share that is being phased out on a schedule — 15 percent for calendar years 2023 through 2026, 10 percent for 2027 through 2029, and none from 1 January 2030 (42 CFR 410.152). On a commercial plan the preventive protection comes from 45 CFR 147.130, which requires coverage of USPSTF grade A and B services without cost sharing; what the individual patient sees still depends on plan design and network status, so we verify it rather than promise it.
Does Medicare cover a follow-up colonoscopy after a positive Cologuard or blood-based test?
Yes, and it is treated as part of the screening rather than as a diagnostic study. 42 CFR 410.37(k), effective 1 January 2025, makes a follow-on screening colonoscopy after a Medicare-covered non-invasive stool-based or blood-based biomarker colorectal cancer screening test returns a positive result part of a complete colorectal cancer screening, and exempts it from the usual frequency limits. Billed that way it carries no Part B deductible. If tissue is removed during that colonoscopy it becomes a converted screening under paragraph (j) and the phased coinsurance applies — 15 percent through calendar year 2026. Billing it as an ordinary diagnostic colonoscopy instead is what wrongly creates a full patient bill.
How often does Medicare cover a screening colonoscopy?
The frequency rules are in 42 CFR 410.37(g), and they are written as elapsed months rather than intervals. For a patient at high risk for colorectal cancer, payment may be made after at least 23 months have passed following the month of the last screening colonoscopy — in practice, once every 24 months. For a patient not at high risk, after at least 119 months, or after at least 47 months if the last test was a screening flexible sigmoidoscopy. The regulation sets a minimum age of 45 for screening fecal occult blood tests, flexible sigmoidoscopy and CT colonography, but states none for screening colonoscopy. Frequency denials almost always trace to the prior screening's date sitting inside one of these windows.
How much do gastroenterology billing services cost?
GI billing pricing follows the percentage-of-collections model, with the rate reflecting endoscopy volume and how much conversion and modifier rework the practice generates. MedPrecision's published rates start at 7.0% of collections for solo practices and 6.0% for group practices of 2 to 15 providers, with no setup fees and no per-claim charges; the solo tier carries a monthly minimum that is set in your quote rather than published. Full tiers are on our pricing page.
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