Gastroenterology billing
Gastroenterology billing services
We handle billing for gastroenterology practices, from office visits to colonoscopies and upper endoscopies done in the office, ASC or hospital. Claims go out within 24 hours of receiving charges, every denial is worked within 5 business days, and pricing starts at 2.5% of collections.
- Screening vs diagnostic colonoscopy coding (G0121, 45378, modifier PT/33)
- EGD and colonoscopy with biopsy or polypectomy
- Benefit checks so screening patients are not surprised by a bill
Why gastroenterology billing is different
One colonoscopy can be billed three different ways
GI billing turns on intent. The same procedure is coded differently depending on why it was ordered, what was found and which payer covers the patient.
Screening that becomes diagnostic
A screening colonoscopy that turns into a biopsy or polyp removal is still reported with a screening indicator. Medicare uses modifier PT; most commercial plans use modifier 33. Leave it off and the patient may get a cost-share bill they should not owe.
Medicare vs commercial screening codes
Medicare screening colonoscopies use HCPCS G0121 (average risk) or G0105 (high risk). Many commercial plans want CPT 45378 with modifier 33 instead. We code to the payer, not to habit.
Diagnosis order matters
For a screening that finds a polyp, the screening Z code usually goes first and the finding second. Getting the order wrong is a common reason screening benefits are not applied.
Multiple endoscopy rules
When an EGD and colonoscopy are done in the same session, or several techniques are used in one scope, payers apply endoscopy family and multiple procedure rules. Modifiers such as 59 or XS are needed only when the rules support them.
Site of service
Procedures in the office, ASC and hospital outpatient department are paid differently. The professional claim must show the right place of service so the fee schedule matches where the work happened.
Prior auth and frequency limits
Some plans require authorization for diagnostic endoscopy, capsule endoscopy or infusion drugs, and all plans limit screening frequency. We check benefits and history before the procedure date.
Common codes
Gastroenterology codes we review on every claim
| Code(s) | What it is | What we watch for |
|---|---|---|
| G0121 / G0105 | Medicare screening colonoscopy (average risk / high risk) | Frequency limits and the risk diagnosis that supports G0105 |
| 45378 | Diagnostic colonoscopy | Modifier 33 when a commercial screening is billed this way |
| 45380 / 45385 | Colonoscopy with biopsy / with snare polyp removal | Modifier PT or 33 when the visit started as a screening |
| 43235 / 43239 | Upper endoscopy (EGD), diagnostic / with biopsy | Multiple endoscopy rules when done with a colonoscopy |
| 91110 | Capsule endoscopy of the small bowel | Prior authorization and medical necessity documentation |
| 99202–99215 | New and established office visits | Pre-procedure visits that are separately billable vs part of the procedure |
Codes and rules change. We check current CPT guidance and each payer’s policy before submission.
Common denials we prevent
GI denials we stop before they happen
Most GI denials come from screening rules, frequency limits and missing authorizations. We catch them at charge entry.
- Screening colonoscopy billed as diagnostic with no PT or 33 modifier
- Screening frequency exceeded because prior procedure history was not checked
- Diagnosis codes listed in an order that blocks the screening benefit
- Biopsy and polypectomy on the same scope billed without the right modifier support
- Missing prior authorization for capsule endoscopy or diagnostic procedures
- Place of service that does not match the facility where the procedure was done
What we handle
Everything between the procedure and the payment
- Insurance eligibility and benefits checks before visits and procedures
- Charge entry and coding review of procedure codes, modifiers and diagnosis order
- Claim submission within 24 hours of receiving charges
- Payment posting and ERA reconciliation
- Denial correction, resubmission and appeals within 5 business days
- A/R follow-up on unpaid and underpaid claims
- Commercial, Medicare and Medicaid credentialing for your gastroenterologists and APPs
- Patient statements and balance tracking
- Monthly reporting on collections, denials and A/R
Pricing
Clear pricing for gastroenterology practices
Billing starts at 2.5% of collections, or a flat monthly fee. There is no setup fee and no long-term contract. Credentialing starts at $80 per payer, and 5 commercial payers are credentialed free when you sign up for billing.
Common questions
How do you bill a screening colonoscopy that turns into a polypectomy?
We bill the therapeutic code (such as 45385) with a screening indicator: modifier PT for Medicare or modifier 33 for most commercial plans, with the screening diagnosis first. Rules vary by payer, so we check each plan’s current policy.
Do you know when to use G0121 instead of 45378?
Yes. Medicare screening colonoscopies use G0121 for average-risk patients and G0105 for high-risk patients. Many commercial payers want 45378 with modifier 33 instead. We code to each payer’s rules.
Can you bill an EGD and colonoscopy on the same day?
Yes. Both can be billed for the same session. We apply multiple procedure rules and add modifiers only when the documentation and payer policy support them.
Do you bill for procedures done at an ASC or hospital?
Yes. We bill the professional claim for procedures in the office, ASC or hospital and make sure the place of service matches the site. The facility bills its own claim separately.
Do you check screening frequency before the procedure?
Yes. We verify eligibility, benefits and prior screening history before the procedure date where the payer makes that information available, so the practice can talk to the patient about cost ahead of time.
Is gastroenterology your main specialty?
No. Our core focus is behavioral health, and we bill gastroenterology and other specialties with the same team, the same promises and CPB-certified billers on the team.
Guides from our team
Learn more before you decide
Top 10 Reasons for Medical Claim Denials (And How to Fix Them Fast)
The 10 most common reasons for medical claim denials, what each one costs your practice, and the exact fix for each. Plus a denial-prevention checklist.
Read the guide →Claim Denial Codes Explained: What CO-16, CO-50, CO-197, PR-1 and Others Mean and How to Fix Them
What common denial codes mean (CO-16, CO-18, CO-50, CO-97, CO-197, PR-1 and more) and how to fix each, for mental health and medical practices.
Read the guide →Medical Billing Services for Small Practices: Complete Guide to Maximizing Revenue
Explore medical billing services for small practices, from claim submission and payment posting to denial follow-up, with practical steps to improve revenue.
Read the guide →Find out what your claims are leaving on the table
Tell us about your practice. We will review 90 days of claims and show you what is recoverable, at no cost.
Prefer to talk? +1 770-520-0840
Thank you. We have your request.
A billing specialist will reply within 1 business hour during business hours (Mon–Fri, 9am–6pm ET). Want to pick a time now?
Book a call on Calendly