Billing code 91034: Reflux monitoringMedicare rate & RVUs in Illinois
Reports ambulatory esophageal acid monitoring with a transnasal catheter to evaluate reflux and correlate recorded acid events with symptoms.
Medicare pays $189.30–$209.23 for 91034 in the office in Illinois, from Rest Of Illinois to Suburban Chicago. Which amount applies depends on the service address.
Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.
On this page 9 sections
What 91034 covers
This service evaluates gastroesophageal reflux by placing a pH-sensing catheter through the nose into the esophagus and recording acid exposure during ambulatory monitoring, commonly over 24 hours. A gastroenterologist or other qualified clinician places the catheter; the study data are analyzed and interpreted to assess acid reflux and its relationship to reported symptoms. It may be used when reflux symptoms persist or when objective acid-exposure data are needed in a reflux evaluation.
Report 91034 for catheter-based pH monitoring, not a wireless capsule study or an impedance-based test. The record should support catheter placement, monitoring, analysis, and interpretation. CMS assigns a 0-day global period, so same-day preoperative and postoperative care is included. Bill the global service without a modifier, or use modifier 26 for interpretation or TC for the technical service. Modifier 50 is inappropriate. Assistant-at-surgery payment requires documented medical necessity; co-surgeons and team surgery are not permitted.
This summary was written with AI assistance from CMS physician fee schedule data and checked against the CMS billing rules shown here. Rates on this page come directly from CMS files.
Where 91034 pays more and less in Illinois
The same RVUs, adjusted for each area’s costs. Open a locality for its calculation, history and nearby areas.
4 payment localities
$189.30 to $209.23
| Payment locality | Office | Facility |
|---|---|---|
| Chicago | $206.93 | Unavailable |
| East St. Louis | $191.68 | Unavailable |
| Rest Of Illinois | $189.30 | Unavailable |
| Suburban Chicago | $209.23 | Unavailable |
How the 91034 rate is calculated
Each of 91034’s three RVUs is multiplied by a geographic index (GPCI) for the payment locality, added up, and multiplied by the conversion factor. Drag the indexes or enter a ZIP to see what moves the rate.
How the rate is built · 91034
RVUs × geographic indexes × conversion factor
Work0.95
0.95 RVUs× 1.000 GPCI
Practice expense5.03
5.03 RVUs× 1.000 GPCI
Malpractice0.08
0.08 RVUs× 1.000 GPCI
Adjusted RVUs
6.0600
Conversion factor
$33.4009
Medicare rate
$202.41
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for 91034
The CMS indicators that decide how 91034 is paid alongside other services.
CMS payment indicators · 91034
Reflux monitoring
| Rule | CMS value | What it means |
|---|---|---|
| Global period | 000 | Same-day global: pre- and post-op care on the day of the procedure is included. |
| Multiple procedures | 0 | No multiple-procedure reduction. |
| Bilateral (modifier 50) | 0 | The 150% bilateral adjustment doesn’t apply. |
| Assistant at surgery (80/81/82/AS) | 0 | Not paid without supporting documentation. |
| Co-surgeons (62) | 0 | Not permitted. |
| Team surgery (66) | 0 | Not permitted. |
| Professional/technical | 1 | Diagnostic test with separate professional (26) and technical (TC) components. |
What modifiers do to the payment
Modifier 26 · payment effect
With and without the modifier
91034 without 26 · national office
$202.41
Reflux monitoring
91034-26 · Professional component
$50.44
Pays only the interpretation and report.
91034 compared with similar codes
Compare codes · National
5 codes, side by side
How to choose
- 91035Reflux testing
- Choose 91034 for pH monitoring with a transnasal catheter; choose 91035 when the study uses wireless pH monitoring.
- 91037Esophageal impedance
- 91037 describes impedance-based reflux testing. Use 91034 when the performed study is catheter-based pH monitoring without impedance.
- 91038Esophageal impedance
- 91038 is an impedance-based reflux test. The presence of impedance in the performed study distinguishes it from 91034.
- 91030Acid challenge
- 91030 is an acid-perfusion test that provokes an esophageal response; 91034 records esophageal acid exposure during pH monitoring.
91034 billing questions
How does 91034 differ from 91035?
91034 is for pH monitoring with a transnasal catheter. 91035 is the wireless pH-monitoring method.
Can the interpretation be billed separately?
Yes. Modifier 26 identifies the professional interpretation; TC identifies the technical service. Without either modifier, the claim represents the global service.
What should the record support?
Document the catheter-based monitoring, recorded study data, analysis, and interpretation. The report should identify the findings relevant to esophageal acid exposure and reflux symptoms.
Should modifier 50 be appended?
No. CMS identifies modifier 50 as inappropriate for this service.
How does 91034 differ from impedance reflux testing?
91034 reports catheter-based pH monitoring. Codes 91037 and 91038 describe impedance-based reflux testing, so code selection follows the test actually performed.
Are same-day care and surgical-team services separately payable?
Same-day preoperative and postoperative care is included in the 0-day global period. Assistant-at-surgery payment requires documented medical necessity, while co-surgeons and team surgery are not permitted.
Where these rates come from
FeeBase calculates base physician payments from CMS work, practice-expense and malpractice RVUs, adjusted by each locality’s geographic indexes and the conversion factor. Services without a published rate are labeled, never given a made-up amount. Amounts are Medicare allowed amounts before claim adjustments: not a patient’s bill or a commercial rate.
CMS RVU26D · effective Oct 1, 2026 through the day before Jan 1, 2027
Show the CMS file lines behind this rate
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