CPT code 91034: Reflux monitoring, nasal catheter pH test2026 Medicare rate & RVUs

Medicare pays $202.41 for 91034 nationally in the office. Local office rates run $177.42–$278.92.

Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.

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

The same RVUs, adjusted for each area’s costs. Open a locality for its calculation, history and nearby areas.

109 of 109 payment localities

91034 rates by state

Office rate range in each state. Select a state to see its payment localities.

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.

Payment rules and modifiers for 91034

The CMS indicators that decide how 91034 is paid alongside other services.

What modifiers do to the payment

When to use modifier 26

91034 compared with similar codes

How to choose

91035Reflux testingMucosa-attached telemetry electrode

Choose 91034 for pH monitoring with a transnasal catheter; choose 91035 when the study uses wireless pH monitoring.

91037Esophageal impedanceOne hour or less

91037 describes impedance-based reflux testing. Use 91034 when the performed study is catheter-based pH monitoring without impedance.

91038Esophageal impedanceMore than one hour

91038 is an impedance-based reflux test. The presence of impedance in the performed study distinguishes it from 91034.

91030Acid challengeProvocative esophageal acid test

91030 is an acid-perfusion test that provokes an esophageal response; 91034 records esophageal acid exposure during pH monitoring.

Codes related to 91034

Related codes aren’t interchangeable: bill the code that matches the service performed.

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

Open CMS sourceHow we calculate rates