CPT 91034: Esophageal reflux test (pH/impedance)
What this code means, what it should cost, and how to dispute an overcharge.
Fair Price Reference
What is CPT 91034?
CPT 91034 (Esophageal reflux test (pH/impedance)) is a gastroenterology billing code defined by the American Medical Association. It's used to bill your insurance or you directly for this service.
What CPT 91034 should cost
The Centers for Medicare & Medicaid Services (CMS) pays approximately $167 for CPT 91034 under the 2025 Physician Fee Schedule. This is what the federal government has determined is a reasonable payment for this service.
Private insurance typically pays 1.2–1.8x Medicare rates ($200–$301). Hospital chargemaster prices for CPT 91034 often range from $350 to $1800 — a markup of 2.1x to 10.8x over Medicare.
Common overcharges on CPT 91034
Inflated charges, bundled services billed separately, and coding errors are common across medical specialties.
About Gastroenterology billing
Medical procedures like this one are frequently overcharged on hospital bills. Comparing your charge against Medicare allowable and requesting an itemized bill are the first steps to identifying errors.
Request your itemized bill, compare charges against Medicare allowable, and dispute any charges exceeding 150% of the Medicare rate.
How to dispute a CPT 91034 overcharge
- Request the itemized bill. You are entitled to a detailed line-by-line bill showing every CPT code billed. Ask in writing.
- Compare to Medicare allowable. If the charge exceeds 150% of Medicare ($251), you have grounds to dispute.
- Request documentation. For E&M codes, ask for the visit note. For procedures, ask for the operative report. The documentation must justify the code billed.
- Send a formal dispute letter. Cite the specific discrepancy between the documentation and the code. Reference Medicare rates and NCCI edits where applicable.
- Follow up in writing. Give the provider 30 days to respond. If they don't, escalate to the state attorney general and insurance commissioner.
Got CPT 91034 on your bill?
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