Gastroenterology billing services
Billing for GI practices and endoscopy centers, with screening and diagnostic colonoscopies, EGDs and add-on procedures coded to each payer's rules.
Why gastroenterology billing takes specialty knowledge
Gastroenterology billing depends on why a scope was done and what happened during it. A screening colonoscopy that finds a polyp becomes a therapeutic procedure, and Medicare and commercial payers report that change differently. Multiple techniques in one session, such as a biopsy of one lesion and a snare removal of another, follow endoscopy family rules and need modifiers to be paid.
SFA Solutions codes GI procedures from the endoscopy report and pathology. We apply PT for Medicare and modifier 33 for commercial plans when screening turns diagnostic, use KX for Medicare follow-on colonoscopy after a positive stool test, bill each technique on separate lesions with the right modifier, and verify authorization for procedures like capsule endoscopy. The aim is fewer surprise bills for patients and fewer claims that need to be corrected and resubmitted.
Common codes we work with in gastroenterology
| Code | Description |
|---|---|
| 45378 | Colonoscopy, diagnostic |
| 45380 | Colonoscopy with biopsy, single or multiple |
| 45385 | Colonoscopy with removal of lesion by snare technique |
| G0121 | Screening colonoscopy, patient not at high risk |
| G0105 | Screening colonoscopy, patient at high risk |
| 43235 | Upper GI endoscopy (EGD), diagnostic |
| 43239 | Upper GI endoscopy (EGD) with biopsy, single or multiple |
| 91110 | GI tract imaging, intraluminal (capsule endoscopy), esophagus through ileum |
CPT is a registered trademark of the American Medical Association. Payer rules vary; we check each payer's current policy.
Where gastroenterology practices lose revenue
Screening that becomes diagnostic
Medicare screening colonoscopies are billed with G0121 (not high risk) or G0105 (high risk). When a polyp is removed, the procedure is billed with the diagnostic or therapeutic CPT code and modifier PT, and in 2026 the patient's coinsurance is 15% of the allowed amount. Commercial plans generally use modifier 33 to show the procedure started as preventive under ACA rules.
Follow-on colonoscopy after a positive stool test
Medicare treats a colonoscopy after a positive stool-based screening test as part of screening, so the patient has no cost sharing for the screening colonoscopy itself. Medicare requires modifier KX on these claims, along with PT if the procedure becomes therapeutic. The anesthesia claim also needs the right modifiers.
Multiple procedures in one session
Colonoscopy codes belong to one endoscopy family, with 45378 as the base. When a biopsy (45380) and a snare polypectomy (45385) are done on different lesions, both are payable, with modifier 59 or XS on the second when the lesions differ. Techniques performed on the same lesion are generally not billed separately.
Prior authorization and medical necessity
Commercial plans often require authorization for capsule endoscopy, motility studies and some EGDs. Repeat surveillance colonoscopies must meet the payer's interval rules based on prior findings. We check both before the procedure date to avoid denials after the fact.
What else affects gastroenterology revenue
A/R challenges in gastroenterology
GI A/R often comes from mismatches between the three claims for one scope: the professional claim, the anesthesia claim and the facility claim. If the screening modifier or diagnosis order differs across them, one claim can be denied or applied to the patient's deductible while the others pay. Screening colonoscopies that become therapeutic also create patient balances, and patients who expected a free screening may dispute them, so those accounts need careful review before statements go out.
Credentialing considerations
Gastroenterologists enroll under taxonomy 207RG0100X and need privileges at each hospital or ASC where they perform procedures. A physician-owned endoscopy center is a separate entity that enrolls with Medicare as an ASC and contracts separately with commercial plans. If the practice employs CRNAs or anesthesiologists for sedation, they need their own enrollment and should be set up so their claims follow the same screening rules.
Payer considerations
Most commercial plans follow the USPSTF recommendation to start average-risk colorectal screening at age 45, and plans must cover a follow-on colonoscopy after a positive stool-based test as part of screening without cost sharing. Medicare covers screening colonoscopy every 10 years for average risk patients and every 24 months for high risk, and the frequency rules are checked by date of last screening. Medicare Advantage plans and some commercial plans require prior authorization for capsule endoscopy and certain diagnostic procedures.
Gastroenterology coding details that affect payment
ICD-10 considerations
Diagnosis order decides how a colonoscopy is paid. A screening exam lists Z12.11 first, followed by any finding such as K63.5 (polyp of colon) or a D12 code for a benign neoplasm by colon segment, and surveillance exams use personal history codes, which were expanded in 2023 to Z86.0100 through Z86.0109 to show the type of prior polyp. Family history of colon cancer (Z80.0) supports high-risk screening intervals. Upper GI claims need specific codes, such as K21.00 (GERD with esophagitis, without bleeding) or the K22.7 Barrett's esophagus codes that show the grade of dysplasia. Crohn's disease and ulcerative colitis use combination codes in K50 and K51 that capture complications such as bleeding or obstruction.
Modifiers to watch
| PT | Appended to the CPT code on a Medicare claim when a colorectal cancer screening test becomes diagnostic or therapeutic, so the deductible is waived. |
|---|---|
| 33 | Used on commercial claims to show that a colonoscopy began as an ACA preventive screening, which affects the patient's cost sharing. |
| KX | Added to a Medicare colonoscopy that follows a positive stool-based screening test, identifying it as a follow-on screening service. |
| 53 | Applied when a scope is started but discontinued because the patient's condition puts them at risk, such as unstable vital signs, and payers differ on 52 versus 53 for incomplete exams due to poor prep. |
| XS or 59 | Used when different techniques are performed on separate lesions in the same session, with each lesion's location documented. |
Global periods
Colonoscopy and EGD codes such as 45378, 45385 and 43239 carry 0-day global periods, so an unrelated visit the next day is separately billable. A visit on the day of the procedure is payable only when it is significant and separate from the usual pre-procedure assessment, with modifier 25.
Medicare considerations
Medicare colorectal screening coverage is set by NCD 210.3, which lists the covered tests, frequencies and the age 45 starting point for average-risk patients. CMS added CT colonography as a covered screening test in 2025, and a follow-on colonoscopy after a positive non-invasive test counts as part of the screening benefit. Many MACs also have local policies for capsule endoscopy and esophageal motility testing that list covered indications.
Gastroenterology billing KPIs to track
- Professional, anesthesia and facility modifier match rate. When the three claims for one scope disagree on screening status, one of them is often denied or shifted to the patient.
- Screening conversion balance disputes. Patients who expected a free screening often dispute coinsurance after a polypectomy, so tracking disputes shows where pre-procedure education is falling short.
- Surveillance interval denials. Repeat colonoscopies denied for frequency point to missing history codes or exams scheduled before the payer's interval.
- Days from procedure to claim. Waiting on pathology for diagnosis coding can delay claims, so tracking the lag keeps pathology holds from becoming aging A/R.
Gastroenterology billing audit checklist
- Confirm Z12.11 is sequenced first on screening colonoscopies that found a polyp.
- Check that PT, 33 or KX is applied to both the professional and anesthesia claims when screening rules apply.
- Verify biopsy and snare codes billed together document separate lesions.
- Review surveillance colonoscopies for a personal history code and the date of the prior exam.
- Confirm capsule endoscopy and motility studies had authorization before the procedure date.
- Compare Medicare screening claims against the last screening date to catch frequency denials before submission.
How SFA runs gastroenterology billing
We verify screening benefits, authorization and surveillance intervals before scheduled procedures.
Coders assign procedure codes and modifiers from the endoscopy report and confirm diagnoses with pathology.
Professional and anesthesia claims are coordinated so screening modifiers match, and most clean claims are submitted within 24 hours.
Denials are worked and patient balances are reviewed to prevent incorrect screening charges.
The services that matter most for gastroenterology
Medical Coding
Screening versus diagnostic coding and endoscopy family rules decide both payment and what the patient owes.
Learn moreEligibility Verification & Prior Authorization
Capsule studies and some EGDs need authorization, and screening benefits should be confirmed before the scope.
Learn moreDenial Management
Frequency and modifier denials on colonoscopies can usually be corrected or appealed with the report.
Learn moreWhat practices typically see with SFA
Averages and selected client results. Your free audit shows where your own numbers stand today.
Target for the claims we manage, not a measured average.
Highest improvement seen in selected client results.
Largest drop in A/R days seen in selected client results.
Targeted for submission within 24 hours after final review.
From primary care and nurse practitioners to surgery and imaging.
We work inside the system your practice already uses.
Results vary by practice, specialty, payer mix, claim volume, billing history, documentation and other factors. Performance figures represent average or selected client results and are not guarantees of future performance. The 95% figure is a clean-claim target, not a measured cohort. The client-results page does not include a measurement period, starting collections, or practice size.
Gastroenterology billing questions
What modifier is used when a screening colonoscopy becomes diagnostic?
For Medicare, bill the diagnostic or therapeutic CPT code with modifier PT. Most commercial plans use modifier 33 to show the procedure started as a preventive service.
What does a Medicare patient owe if a polyp is removed?
In 2026 the coinsurance for a screening colonoscopy that becomes therapeutic is 15% of the allowed amount. The Part B deductible does not apply. Under current law the coinsurance drops to 10% from 2027 through 2029 and to zero in 2030.
Can I bill a biopsy and a polypectomy in the same colonoscopy?
Yes, when they are performed on different lesions. Bill 45380 and 45385 with modifier 59 or XS on the second code and document each lesion's location.
When is modifier KX used on colonoscopy claims?
Medicare requires KX on a colonoscopy that follows a positive stool-based screening test, such as a FIT or multi-target stool DNA test. It identifies the procedure as a follow-on screening service.
Do you bill for endoscopy centers too?
We bill professional services for gastroenterologists and can work with ASC billing teams so facility, professional and anesthesia claims use matching codes and modifiers.
See what your gastroenterology billing is missing
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