CPT code 91038: Esophageal impedance, more than one hour2026 Medicare rate & RVUs

Medicare pays $445.90 for 91038 nationally in the office. Local office rates run $387.29–$628.37.

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

What 91038 covers

A thin catheter with impedance sensors is passed through the nose into the esophagus to record movement of swallowed material and reflux over a prolonged period. The test can help evaluate persistent heartburn, regurgitation, or other suspected reflux symptoms, including symptoms that continue during acid-suppressing treatment. It is typically performed in a gastroenterology or motility laboratory, with a physician interpreting the recording and reporting the findings.

Select this service for impedance monitoring lasting more than one hour, rather than the shorter-duration service. Documentation should support catheter placement, the recording period, analysis, and interpretation. CMS recognizes professional and technical components: modifier 26 identifies interpretation, modifier TC identifies equipment and staff, and no component modifier represents the global service. The 0-day global period includes same-day preoperative and postoperative care. 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 91038 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

91038 rates by state

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

How the 91038 rate is calculated

Each of 91038’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 91038

The CMS indicators that decide how 91038 is paid alongside other services.

What modifiers do to the payment

When to use modifier 26

91038 compared with similar codes

How to choose

91037Esophageal impedanceOne hour or less

Both report esophageal impedance testing; choose 91038 when the recording exceeds one hour and 91037 for the shorter-duration service.

91034Reflux monitoringNasal catheter pH test

91034 measures esophageal acidity with a catheter. This code reports prolonged impedance monitoring, which detects movement of material through the esophagus.

91035Reflux testingMucosa-attached telemetry electrode

91035 uses a wireless pH electrode for reflux monitoring. This code reports catheter-based impedance monitoring.

91010Esophageal manometryStandard pressure study

91010 evaluates esophageal motility with manometry. This code evaluates reflux-related events with impedance monitoring.

Codes related to 91038

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