CPT 91037: Gastroesophageal Reflux Monitoring with Transnasal Impedance

CPT code 91037 represents ambulatory gastroesophageal reflux monitoring using a transnasal catheter with intraluminal impedance electrode placement; the provider records and interprets the test report. This diagnostic procedure is used to detect and characterize acid and non-acid reflux events, informing management of reflux-related symptoms and guiding therapeutic decisions. Nationally, accurate coding and consistent use of 91037 matter for clinical documentation, quality measurement, and claims processing for outpatient gastroenterology services.

Key payers covered include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of clinical intent and typical sites of service, a summary of payer coverage considerations, and benchmarking context where available. The publication highlights coding specifics for the procedure, common modifiers listed in payer policies, and operational considerations for ambulatory monitoring programs. It also situates 91037 within broader diagnostic workflows for gastroesophageal reflux disease and related symptom evaluation.

Data not available in the input for associated taxonomies, specific ICD-10 diagnoses, and payer-specific reimbursement rates.

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Billing Code Overview

CPT code 91037 describes a gastroesophageal reflux test that assesses the backflow of stomach acid into the esophagus using a nasal catheter with intraluminal impedance electrode placement. The provider places the nasal catheter, records the monitoring session, and interprets the resulting report.

Service type: Ambulatory physiologic reflux monitoring with transnasal intraluminal impedance
Typical site of service: Ambulatory clinic or outpatient diagnostic laboratory (transnasal catheter placement and ambulatory monitoring)

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CPT 91037: Gastroesophageal Reflux Monitoring with Transnasal Impedance

Data not available in the input for associated taxonomies, specific ICD-10 diagnoses, and payer-specific reimbursement rates.

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Get alerted when payer policies referencing 91037 are released or updated.

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Billing Code Overview

Service type: Ambulatory physiologic reflux monitoring with transnasal intraluminal impedance
Typical site of service: Ambulatory clinic or outpatient diagnostic laboratory (transnasal catheter placement and ambulatory monitoring)

Clinical & Coding Specifications

Clinical Context

A 45-year-old patient presents to a gastroenterology clinic with chronic heartburn, regurgitation, and atypical chest pain despite proton pump inhibitor therapy. The gastroenterologist recommends ambulatory esophageal reflux testing using a combined intraluminal impedance and pH catheter placed transnasally to quantify acid and non-acid reflux events and correlate symptoms. The procedure is performed in the outpatient endoscopy suite: topical nasal anesthesia is applied, a combined impedance-pH catheter is advanced transnasally and positioned with the impedance electrodes and pH sensor across the distal esophagus, correct positioning is confirmed, and the catheter is secured. The provider collects ambulatory recording data for the prescribed monitoring period, retrieves the device/report, reviews impedance/pH tracings, and documents interpretation and a formal report. Typical site of service is an outpatient ambulatory surgery center or gastroenterology clinic with monitoring equipment; the service type is diagnostic ambulatory esophageal impedance-pH monitoring. Common payors include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, BUCA, and Medicare.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`K21.0`	Gastro-esophageal reflux disease with esophagitis	Common indication for impedance-pH testing to document acid reflux and correlate symptoms.
`K21.9`	Gastro-esophageal reflux disease without esophagitis	Used when patients have reflux symptoms but no endoscopic findings; ambulatory impedance-pH testing can confirm reflux.
`R07.9`	Chest pain, unspecified	Reflux testing may be used to evaluate non-cardiac chest pain suspected to be reflux-related.
`R06.2`	Shortness of breath	Used when reflux is suspected to contribute to respiratory symptoms; testing can aid correlation.
`R05`	Cough	Chronic cough potentially related to reflux frequently prompts impedance-pH monitoring to assess reflux-related cough correlation.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`91034`	Esophageal impedance testing, placement of transnasal impedance catheter (without pH)	Alternative or component testing when only impedance without pH monitoring is performed; may be performed when non-acid reflux is the primary concern.
`91036`	Placement of nasopharyngeal catheter for pH monitoring and interpretation (ambulatory)	Related code when only pH monitoring (without impedance) is performed; may be used in workflows where impedance is not available.
`43235`	Esophagoscopy, flexible, transoral; diagnostic, with or without collection of specimen(s) by brushing or washing	Performed before or in conjunction with reflux evaluation to assess mucosal disease or obtain biopsies if indicated.
`91040`	Esophageal reflux testing; insertion and removal of transnasal catheter with analysis only	Used in select workflows for limited monitoring services or analysis-only billing scenarios.
`94060`	Continuous overnight oximetry; in-home or in-hospital, single or multiple determinations	Performed concurrently in some patients to correlate reflux events with oxygen desaturation or respiratory symptoms in selected clinical scenarios.

Related Modifiers

8 rows

Modifier	Description	When to Use
26	Modifier 26 (Professional Component) identifies and bills only the professional portion of a split service — the physician’s interpretation, report, and medical judgment — when the technical…	- Use CPT Modifier -26 when you are billing only the professional component (PC) of a split‑bill eligible service—i.e., you performed the physician interpretation, medical judgment and prepared a…
59	Modifier 59 indicates a distinct procedural service when two procedures that are not normally billed together are clinically and procedurally separate. The CPT definition (as reiterated by CMS)…	- Use modifier -59 to report a distinct procedural service when documentation supports that the procedure reported is not normally billed together with another service on the same day because of a…
52	Modifier ‑52 (Reduced Services) indicates that a service or procedure was partially reduced or omitted at the provider’s discretion, allowing reporting of the basic procedure number with a qualifier…	- Use modifier -52 when a physician or qualified health professional electively reduces or omits part of a procedure or service (for example, performing fewer required views or omitting a portion of…
53	Modifier 53 (Discontinued Procedure) signals that a surgical or diagnostic service was begun by the physician but terminated because of extenuating circumstances that threatened the patient’s…	- Use modifier -53 when a physician/qualified healthcare professional has started a surgical or diagnostic procedure (e.g., anesthesia administered, incision or scope insertion) and then discontinues…
76	Modifier -76, Repeat Procedure or Service by Same Physician or Other Qualified Health Care Professional, is appended when the same provider performs an identical, medically necessary procedure or…	- Use modifier -76 when the same physician or other qualified health care professional performs an identical procedure or service a second (or subsequent) time on the same date of service and the…
77	Modifier 77 indicates that a previously performed procedure or service was legitimately repeated by a different physician or other qualified health care professional. The AMA’s CPT definition…	- Use modifier 77 when a basic procedure or service already performed is repeated by a different physician or other qualified health care professional (for example, a second provider independently…
22	Modifier –22 (Increased Procedural Services) is used when a reported procedure is substantially more extensive than normally required. The CPT Manual and CMS state it may be appended only when the…	- When to use: Append modifier -22 to a procedural CPT code when the service performed is substantially more extensive than the usual service described by that code — i.e., the procedure required…
25	CPT modifier 25 indicates that on the same day as another procedure or service, the same physician or other qualified health care professional provided a significant, separately identifiable…	- When to apply: Use modifier 25 only on an E/M code to indicate the same provider delivered a significant, separately identifiable E/M service on the same day as another procedure or service — i.e.,…

Related Provider Taxonomies

8 rows

Taxonomy Code	Specialty	Notes
207K00000X	Allergy & Immunology Physician	An allergist-immunologist is trained in evaluation, physical and laboratory diagnosis, and management of disorders involving the immune system. Select…
207L00000X	Anesthesiology Physician	An anesthesiologist is trained to provide pain relief and maintenance, or restoration, of a stable condition during and immediately following an opera…
207Y00000X	Otolaryngology Physician	An otolaryngologist-head and neck surgeon provides comprehensive medical and surgical care for patients with diseases and disorders that affect the ea…
1223X2210X	Orofacial Pain Dentistry	A dentist who assesses, diagnoses, and treats patients with complex chronic orofacial pain and dysfunction disorders, oromotor and jaw behavior disord…
246ZE0500X	EEG Specialist/Technologist	Technologists, Technicians & Other Technical Service Providers · Specialist/Technologist, Other
101YS0200X	School Counselor	Behavioral Health & Social Service Providers · Counselor
2279E1000X	Educational Registered Respiratory Therapist	The focus of patient and family education activities is to promote knowledge of disease process, medical therapy, and self help. Respiratory therapis…
2865M2000X	Military General Acute Care Hospital	A Department of Defense (DoD) health care organization furnishing inpatient care 24 hours per day in "fixed" facilities, primarily for DoD beneficiari…

CPT 91030: Bernstein Test for Acid-Induced Heartburn

CPT-91034-GASTROESOPHAGEAL-PH-MONITORING-PH-PROBE-PLACEMENT

CPT 91034: Gastroesophageal Reflux pH Monitoring with Electrode Placement

CPT-91035-TELEMETRY-PH-ESOPHAGEAL-REFLUX-TESTING

CPT 91035: Telemetry pH Monitoring for Gastroesophageal Reflux

CPT-91038-AMBULATORY-IMPEDANCE-PH-REFLUX-MONITORING

CPT 91038: Ambulatory Impedance-pH Gastroesophageal Reflux Monitoring

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.

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Clinical & Coding Specifications

Clinical Context

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`K21.0`	Gastro-esophageal reflux disease with esophagitis	Common indication for impedance-pH testing to document acid reflux and correlate symptoms.
`K21.9`	Gastro-esophageal reflux disease without esophagitis	Used when patients have reflux symptoms but no endoscopic findings; ambulatory impedance-pH testing can confirm reflux.
`R07.9`	Chest pain, unspecified	Reflux testing may be used to evaluate non-cardiac chest pain suspected to be reflux-related.
`R06.2`	Shortness of breath	Used when reflux is suspected to contribute to respiratory symptoms; testing can aid correlation.
`R05`	Cough	Chronic cough potentially related to reflux frequently prompts impedance-pH monitoring to assess reflux-related cough correlation.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`91034`	Esophageal impedance testing, placement of transnasal impedance catheter (without pH)	Alternative or component testing when only impedance without pH monitoring is performed; may be performed when non-acid reflux is the primary concern.
`91036`	Placement of nasopharyngeal catheter for pH monitoring and interpretation (ambulatory)	Related code when only pH monitoring (without impedance) is performed; may be used in workflows where impedance is not available.
`43235`	Esophagoscopy, flexible, transoral; diagnostic, with or without collection of specimen(s) by brushing or washing	Performed before or in conjunction with reflux evaluation to assess mucosal disease or obtain biopsies if indicated.
`91040`	Esophageal reflux testing; insertion and removal of transnasal catheter with analysis only	Used in select workflows for limited monitoring services or analysis-only billing scenarios.
`94060`	Continuous overnight oximetry; in-home or in-hospital, single or multiple determinations	Performed concurrently in some patients to correlate reflux events with oxygen desaturation or respiratory symptoms in selected clinical scenarios.

Related Modifiers

8 rows

Modifier	Description	When to Use
26	Modifier 26 (Professional Component) identifies and bills only the professional portion of a split service — the physician’s interpretation, report, and medical judgment — when the technical…	- Use CPT Modifier -26 when you are billing only the professional component (PC) of a split‑bill eligible service—i.e., you performed the physician interpretation, medical judgment and prepared a…
59	Modifier 59 indicates a distinct procedural service when two procedures that are not normally billed together are clinically and procedurally separate. The CPT definition (as reiterated by CMS)…	- Use modifier -59 to report a distinct procedural service when documentation supports that the procedure reported is not normally billed together with another service on the same day because of a…
52	Modifier ‑52 (Reduced Services) indicates that a service or procedure was partially reduced or omitted at the provider’s discretion, allowing reporting of the basic procedure number with a qualifier…	- Use modifier -52 when a physician or qualified health professional electively reduces or omits part of a procedure or service (for example, performing fewer required views or omitting a portion of…
53	Modifier 53 (Discontinued Procedure) signals that a surgical or diagnostic service was begun by the physician but terminated because of extenuating circumstances that threatened the patient’s…	- Use modifier -53 when a physician/qualified healthcare professional has started a surgical or diagnostic procedure (e.g., anesthesia administered, incision or scope insertion) and then discontinues…
76	Modifier -76, Repeat Procedure or Service by Same Physician or Other Qualified Health Care Professional, is appended when the same provider performs an identical, medically necessary procedure or…	- Use modifier -76 when the same physician or other qualified health care professional performs an identical procedure or service a second (or subsequent) time on the same date of service and the…
77	Modifier 77 indicates that a previously performed procedure or service was legitimately repeated by a different physician or other qualified health care professional. The AMA’s CPT definition…	- Use modifier 77 when a basic procedure or service already performed is repeated by a different physician or other qualified health care professional (for example, a second provider independently…
22	Modifier –22 (Increased Procedural Services) is used when a reported procedure is substantially more extensive than normally required. The CPT Manual and CMS state it may be appended only when the…	- When to use: Append modifier -22 to a procedural CPT code when the service performed is substantially more extensive than the usual service described by that code — i.e., the procedure required…
25	CPT modifier 25 indicates that on the same day as another procedure or service, the same physician or other qualified health care professional provided a significant, separately identifiable…	- When to apply: Use modifier 25 only on an E/M code to indicate the same provider delivered a significant, separately identifiable E/M service on the same day as another procedure or service — i.e.,…

Related Provider Taxonomies

8 rows

Taxonomy Code	Specialty	Notes
207K00000X	Allergy & Immunology Physician	An allergist-immunologist is trained in evaluation, physical and laboratory diagnosis, and management of disorders involving the immune system. Select…
207L00000X	Anesthesiology Physician	An anesthesiologist is trained to provide pain relief and maintenance, or restoration, of a stable condition during and immediately following an opera…
207Y00000X	Otolaryngology Physician	An otolaryngologist-head and neck surgeon provides comprehensive medical and surgical care for patients with diseases and disorders that affect the ea…
1223X2210X	Orofacial Pain Dentistry	A dentist who assesses, diagnoses, and treats patients with complex chronic orofacial pain and dysfunction disorders, oromotor and jaw behavior disord…
246ZE0500X	EEG Specialist/Technologist	Technologists, Technicians & Other Technical Service Providers · Specialist/Technologist, Other
101YS0200X	School Counselor	Behavioral Health & Social Service Providers · Counselor
2279E1000X	Educational Registered Respiratory Therapist	The focus of patient and family education activities is to promote knowledge of disease process, medical therapy, and self help. Respiratory therapis…
2865M2000X	Military General Acute Care Hospital	A Department of Defense (DoD) health care organization furnishing inpatient care 24 hours per day in "fixed" facilities, primarily for DoD beneficiari…

CPT 91030: Bernstein Test for Acid-Induced Heartburn

CPT-91034-GASTROESOPHAGEAL-PH-MONITORING-PH-PROBE-PLACEMENT

CPT 91034: Gastroesophageal Reflux pH Monitoring with Electrode Placement

CPT-91035-TELEMETRY-PH-ESOPHAGEAL-REFLUX-TESTING

CPT 91035: Telemetry pH Monitoring for Gastroesophageal Reflux

CPT-91038-AMBULATORY-IMPEDANCE-PH-REFLUX-MONITORING

CPT 91038: Ambulatory Impedance-pH Gastroesophageal Reflux Monitoring

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.

Published by

Trek Health powers OpenPayer with a leading commercial payer intelligence platform, seamlessly converting fragmented payer data into actionable insights for provider organizations.

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CPT 91037: Gastroesophageal Reflux Monitoring with Transnasal Impedance

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Billing Code Overview

OpenPayer

CPT 91037: Gastroesophageal Reflux Monitoring with Transnasal Impedance

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Billing Code Overview

Clinical & Coding Specifications

Clinical Context

Related Diagnoses

Related CPT Codes

Related Modifiers

Related Provider Taxonomies

Related Codes

References

Clinical & Coding Specifications

Clinical Context

Related Diagnoses

Related CPT Codes

Related Modifiers

Related Provider Taxonomies

Related Codes

References