CPT code 91035 – Wireless esophageal pH monitoring

Key takeaways

CPT code 91035 reports wireless capsule pH monitoring, while catheter-based studies belong to 91034.

Pair the claim with K21.0 or K21.9 and document the failed PPI trial, or expect a medical necessity denial.

Modifier -26 applies when the physician interprets without owning the equipment, and -TC covers the facility’s technical component.

Medicare skips prior authorization, but most commercial plans want it before the capsule goes in.

Practice management software like Pabau submits the claim electronically and reports denial rates by CPT code.

CPT code 91035 reports a 48- to 96-hour wireless pH study

CPT code 91035 is the AMA-maintained procedure code for a gastroesophageal reflux test using a mucosal attached telemetry pH electrode.

The Medtronic Bravo capsule is the device billed under it in almost every case. A gastroenterologist clips the capsule to the esophageal mucosa during an endoscopy. It then transmits pH readings to a recorder the patient carries for 48 to 96 hours, before detaching on its own.

The code carries a 0-day global period, so pre- and post-procedure evaluation and management services stay separately billable. Place of service moves the payment a long way, which the settings section below covers.

Choosing between 91034 and 91035 comes down to the hardware

91034 covers a catheter-based study, run through the nose and usually recorded over 24 hours. 91035 covers the wireless capsule, placed endoscopically and recorded over 48 to 96 hours.

Mixing the two is the second most common source of denials on esophageal pH claims, behind medical necessity.

Billing 91034 and 91035 on the same date of service for one patient triggers an NCCI edit denial. Check the current CMS NCCI edit pairs before you submit if both studies were ordered.

The ICD-10 code you pair with 91035 decides medical necessity

Medical necessity is the single biggest denial driver on this code. The claim has to pair the procedure with an ICD-10 code that your MAC’s Local Coverage Determination (LCD) accepts.

The diagnoses below are the ones that usually clear, although the covered list differs by contractor.

LCD policies for esophageal pH monitoring vary by MAC jurisdiction, and Novitas, CGS and WPS each publish their own criteria. Confirm the diagnosis sits on your contractor’s covered list before the claim goes out, not after the remittance arrives.

Who owns the Bravo equipment decides your modifier

Modifier choice on 91035 turns on two questions. Who owns the recording equipment, and where did the service happen? Apply the wrong modifier, or leave it off when split billing applies, and the payment comes back short.

A physician employed by a hospital-based GI practice normally needs -26, because the facility owns the Bravo system. Private-practice gastroenterologists who own their equipment bill the global code in an office setting, with no modifier at all. Verify the split billing rules with your MAC before assuming global billing applies.

Reimbursement for 91035 shifts with setting and locality

Medicare reimbursement for 91035 comes from the CMS Physician Fee Schedule. Facility and non-facility rates differ, because the non-facility rate carries a higher practice expense component.

The physician absorbs the equipment and supply costs in that setting. Geographic Practice Cost Index (GPCI) adjustments then pay an identical claim differently in Manhattan and rural Mississippi.

For current RVU-based calculations, the FastRVU 2026 RVU lookup returns Work, Practice Expense and Malpractice RVU values for 91035 with your locality applied. Rates change every year, so confirm against the current MPFS before you quote a patient or set an internal benchmark.

Commercial coverage varies more than Medicare’s does. Aetna’s Clinical Policy Bulletin and the BCBS medical policy pages both set out criteria for esophageal pH monitoring. Three themes repeat across the major plans.

• Prior authorization is required more often than not.
• Coverage usually depends on a documented failed PPI trial.
• Some plans treat 91034 as the covered first study, so wireless monitoring needs written justification.

Medicare skips prior authorization but commercial plans rarely do

Medicare does not require prior authorization for 91035. Most commercial payers do, and the requirement can change mid-year without notice. Policies also differ inside the same payer network, sometimes down to the employer group.

Verify benefits before you schedule the procedure, then confirm the prior authorization rule for 91035 specifically at each visit. Payers usually ask for some combination of the following.

• Documented failed trial of proton pump inhibitor (PPI) therapy, typically 4 to 8 weeks
• Persistent GERD symptoms despite medical management
• Prior upper endoscopy results (EGD report) within a defined lookback period
• Physician attestation that wireless monitoring is necessary over a catheter-based study
• Referral from a primary care or internal medicine physician, on some plans

Submit the request with the complete clinical note, the PPI trial documentation, and the EGD report attached. An incomplete submission is the fastest route to a retrospective denial, arriving after the capsule has already been placed.

Two documents carry a 91035 claim through an audit

The procedure note and the interpretation report each have to stand on their own. An auditor reads them separately, so a detail recorded only in the other document does not count in your favor.

The procedure note must contain:

• Clinical indication for pH monitoring, including PPI trial duration and outcome
• Capsule placement method, with the site referenced to the squamocolumnar junction
• Confirmation of capsule attachment and recording initiation
• Patient instructions for diary completion during the monitoring period
• Provider signature and date

The interpretation report must contain:

• Recording duration, for example 48 hours or 72 hours
• DeMeester score or an equivalent acid exposure time calculation
• Correlation of pH tracings with the patient’s symptom diary entries
• Physician interpretation and clinical conclusion
• Physician signature, identifying the interpreting provider

A structured note that auto-populates from the chart saves the coder from re-keying procedure details out of a PDF. That re-keying step is where most transcription errors start.

Five denial patterns account for most 91035 rejections

Five patterns cover the large majority of 91035 rejections across Medicare and commercial plans. Working them at the code level beats appealing claim by claim, because one root cause keeps producing the same denial.

The CARC codes on the 835 remittance tell you which category you are in. Reading them against the standard denial codes points you at the right appeal route. Review remittances in batches rather than one claim at a time, and the pattern shows up much faster.

Place of service changes what 91035 actually pays

The place of service (POS) code decides which fee schedule rate applies and which parts of the service you can bill separately. It changes what the practice collects for identical clinical work.

Facility and non-facility reimbursement for 91035 sit a long way apart. A private GI practice that owns its Bravo system collects the full non-facility rate.

A hospital-employed gastroenterologist collects the lower facility-rate professional fee, and the hospital bills the technical component separately under the APC system. Multi-setting GI groups need both figures in their fee schedule.

The 910xx codes that sit next to 91035 on a claim

Gastroenterology coders have to keep 91035 apart from the neighboring 910xx codes, because several of them trigger NCCI edits on a shared claim. The endoscopy code 43235 comes up most often, since it is how the capsule gets placed in the first place.

The AAPC Codify CPT lookup is a useful commercial reference for the 910xx family. Check descriptors and edit relationships there before a complex GI claim goes out.

Run these checks before the 91035 claim goes out

A 91035 claim passes six checkpoints between the order and the payment. Each one has a single item that has to be on record, and each one produces a predictable denial when that item is missing.

Work the list below in that order, and most of the five denial patterns never reach the payer.

• Prior authorization number on file, or a note that the plan does not require one
• ICD-10 code checked against your MAC’s current covered-diagnosis list
• PPI trial dates and outcome recorded in the clinical note
• Procedure note naming the placement site and confirming attachment
• Interpretation report carrying recording duration, acid exposure time, and a signature
• Modifier -26 or -TC matched to who owns the equipment
• POS code matching where the capsule was actually placed
• One esophageal pH code only, on that date of service

How Pabau keeps 91035 documentation and claims in one place

Most GI practices run this workflow across three systems. The endoscopy note lives in the EHR, the prior authorization sits in a spreadsheet, and the claim leaves from a separate billing tool. Details get re-keyed at every handover, and that is where the transcription errors begin.

Pabau is practice management software that keeps the record and the claim together. The Bravo procedure note, the interpretation report and the patient’s uploaded documents all attach to the record the charge is raised from.

Our claims management software then submits that charge electronically through Claim.MD, our US clearinghouse partner, which reaches thousands of payers.

Reporting closes the loop. Denial rates break down by CPT code, by payer and by rendering provider. You can see at a glance whether 91035 rejections cluster around one contractor or one clinician. That turns a recurring denial into a single fix rather than a queue of appeals.

Keep GI notes and claims in one system

Pabau’s claims management tools attach the 91035 procedure note to the charge and report denial rates by CPT code. Clean claims go out through Claim.MD, which reaches thousands of payers. See how it works for your practice.

Book a demo

Conclusion

91035 rewards preparation far more than it rewards appeal writing. The prerequisites all sit upstream of the claim. They are the diagnosis you chose, the PPI trial you documented, and the authorization you secured before the capsule went in. Get those right and the denial queue shrinks on its own.

Pick one denial reason from the table above and audit last quarter’s 91035 claims against it. A single pass like that usually explains more rejections than a month of individual appeals. Then build the answer into your procedure note template, so the next claim carries it by default.

Practices that keep the note, the charge and the remittance in one system spend much less time reconstructing what happened six weeks ago. Book a demo to see how Pabau handles a GI claim from the endoscopy note through to the 835.

Continue your research

Need guidance on how clearinghouse claims submission works? Pabau’s Claim.MD clearinghouse guide explains how electronic claims reach payers and how ERA responses map to denial codes.

Billing the motility study alongside the pH test? CPT code 91010 covers the esophageal motility study that often precedes a wireless pH capsule referral.

Taking a biopsy at the same endoscopy? CPT code 43239 sets out the documentation an EGD with biopsy needs when it shares a date of service.

Troubleshooting a denied GI claim? Credentialing with insurance companies covers the provider enrollment steps that prevent claim-level rejections before they start.

Frequently asked questions