Medical Policy: 02.01.03 

Original Effective Date: September 2004 

Reviewed: September 2019 

Revised: September 2019 



This policy contains information which is clinical in nature. The policy is not medical advice. The information in this policy is used by Wellmark to make determinations whether medical treatment is covered under the terms of a Wellmark member's health benefit plan. Physicians and other health care providers are responsible for medical advice and treatment. If you have specific health care needs, you should consult an appropriate health care professional. If you would like to request an accessible version of this document, please contact customer service at 800-524-9242.


Benefit Application:

Benefit determinations are based on the applicable contract language in effect at the time the services were rendered. Exclusions, limitations or exceptions may apply. Benefits may vary based on contract, and individual member benefits must be verified. Wellmark determines medical necessity only if the benefit exists and no contract exclusions are applicable. This medical policy may not apply to FEP. Benefits are determined by the Federal Employee Program.


This Medical Policy document describes the status of medical technology at the time the document was developed. Since that time, new technology may have emerged or new medical literature may have been published. This Medical Policy will be reviewed regularly and be updated as scientific and medical literature becomes available.



Acid reflux is the cause of heartburn, acid regurgitation peptic esophagitis, and Barrett's esophagus, and can cause esophageal stricture, some cases of asthma, posterior laryngitis, chronic cough, dental erosions, chronic hoarseness, pharyngitis subglottic stenosis or stricture, nocturnal choking, and recurrent pneumonia.


When acid repeatedly refluxes from the stomach into the esophagus alone, it is known as gastroesophageal reflux disease (GERD). However, if the stomach acid travels up the esophagus and spills into the throat or pharynx/larynx, is known as laryngopharyngeal reflux (LPR).


Gastroesophageal reflux disease (GERD) is usually diagnosed by clinical history and endoscopy, it is treated empirically with a trial of medical management, of at least four weeks in adults and two weeks in infants, prior to the need for esophageal ph monitoring.


Esophageal ph Monitoring

Esophageal monitoring is done through the use of a tube with a pH electrode attached to its tip, which is then passed to 5 cm above the upper margin of the lower esophageal sphincter (LES). The electrode is attached to a data logger worn on a waist belt or shoulder strap. Every instance of acid reflux as well as its duration and pH is recorded, indicating gastric acid reflux over a 24-hour period.


Wireless Esophageal ph Monitoring

More recently, a catheter-free, temporarily implanted device (Bravo™ pH Monitoring System, marketed by Medtronic) has been approved by the U.S. Food and Drug Administration (FDA) for the purposes of esophageal monitoring in those 4 years old and greater. Using endoscopic or manometric guidance, the capsule is temporarily implanted in the esophageal mucosa using a pin. The capsule records pH levels for up to 96 hours and transmits them via radio frequency telemetry to a receiver worn in the patient's belt. Data from the recorder are uploaded to a computer for analysis by a nurse or doctor.


Impedence ph Monitoring (MII-pH)

Another technology closely related to pH monitoring is impedance-pH monitoring, which incorporates pH monitoring with measurement of impedance, a method of measuring reflux of liquid or gas of any pH. Multiple electrodes are placed along the length of the esophageal catheter. The impedance pattern detected can determine the direction of flow and the substance (liquid or gas). Impedance monitoring is able to identify reflux events in which the liquid is only slightly acidic or non-acidic.  The therapeutic treatment of an abnormal impedance test is unproven at this time. Therefore, the need for testing is not proven at this time.


Impedance Monitoring without ph Testing (MII)

Multichannel Intraluminal Impedance (MII) technology was designed to allow characterization of bolus movement within the esophagus regardless of the pH level. It provides 2 testing modalities in the evaluation of GERD. Esophageal function testing (EFT) combines MII with standard pressure manometry. In context of esophageal bolus transit, measurement of bolus clearance with internal impedance does not determine the abnormal functioning of the esophagus, especially in terms of minor malformations.


Guidelines and Position Statements

American Gastroenterology Association (2011)

The AGA's medical position statement on the management of Barrett's esophagus (2011) noted that "The guideline developers recommend against attempts to eliminate esophageal acid exposure (proton pump inhibitors [PPIs] in doses greater than once daily, esophageal pH monitoring to titrate PPI dosing, or antireflux surgery) for the prevention of esophageal adenocarcinoma (strong recommendation, moderate-quality evidence)".


American Gastroenterological Association (2013)

In 2013, ACG published guidelines on the diagnosis and management of gastroesophageal reflux disease (GERD). The guidelines stated “ambulatory esophageal reflux monitoring is indicated before consideration of endoscopic or surgical therapy in patients with nonerosive disease, as part of the evaluation of patients refractory to PPI therapy, and in situations when the diagnosis of GERD is in question.” This was a strong recommendation based on a low level of evidence. The guidelines noted there is limited evidence and lack of clear consensus on how testing should be performed (eg, catheter-based pH, wireless pH, or impedance pH) for refractory GERD.


Esophageal manometry is recommended for preoperative evaluation, but has no role in the diagnosis of GERD (Strong recommendation, low level of evidence).


Ambulatory esophageal reflux monitoring is indicated before consideration of endoscopic or surgical therapy in patients with non-erosive disease, as part of the evaluation of patient’s refractory to PPI therapy, and in situations when the diagnosis of GERD is in question. (Strong recommendation, low level of evidence). Ambulatory reflux monitoring is the only test that can assess reflux symptom association (strong recommendation, low level of evidence).


Ambulatory reflux monitoring is not required in the presence of short or long-segment Barrett’s esophagus to establish a diagnosis of GERD (Strong recommendation, moderate level of evidence).


Clinical Practice Update Committee of the AGA Institute

The functional luminal imaging probe is a Food and Drug Administration–approved measurement tool used to measure simultaneous pressure and diameter to guide management of various upper gastrointestinal disorders. Additionally, this tool is also approved to guide therapy during bariatric procedures and specialized esophageal surgery. Although it has been commercially available since 2009 as the endolumenal functional lumen imaging probe (EndoFLIP), the functional luminal imaging probe has had limited penetrance into clinical settings outside of specialized centers. This is primarily because of a paucity of data supporting its utility in general practice and a lack of standardized protocols and data analysis methodology. However, data are accumulating that are providing guidance regarding emerging applications in the evaluation and management of foregut disorders. This clinical practice update describes the technique and reviews potential indications in achalasia, eosinophilic esophagitis, and gastroesophgeal reflux disease.


Best Practice Advice 1: Clinicians should not make a diagnosis or treatment decision based on functional lumen imaging probe (FLIP) assessment alone.


Best Practice Advice 2: FLIP assessment is a complementary tool to assess esophagogastric junction opening dynamics and the stiffness of the esophageal wall.


Best Practice Advice 3: Utilization should follow distinct protocols and analysis paradigms based on the disease state of interest.


Best Practice Advice 4: Clinicians should not utilize FLIP in routine diagnostic assessments of gastroesophageal reflux disease.


Best Practice Advice 5: FLIP should not be used to diagnose eosinophilic esophagitis but may have a role in severity assessment and therapeutic monitoring.


American College of Gastroenterology (2007)

The ACG released practice guidelines on esophageal reflux testing. Impedance-pH monitoring was cited as “may be useful” for evaluation of patients with insufficient response to medical therapy. Current interpretation of impedance monitoring relies on use of symptom correlation measures (SI, SSI or SAP). The therapeutic implications of an abnormal impedance test are unproven at this time.


Society of American Gastrointestinal and Endoscopic Surgeons (SAGES 2013)

Ambulatory reflux monitoring is not required in the presence of short or long-segment Barrett’s esophagus to establish a diagnosis of GERD. (Strong recommendation, moderate level of evidence).


International Consensus on Assessment of Oropharangeal Dysphagia (2017)

In terms of objective investigations for OD, there are 5 main exams cited in the literature (functional endoscopic evaluation of swallowing (FEES), video fluoroscopic swallowing study (VFSS), esophageal manometry, pharyngeal pH monitoring, esophageal impedance pH monitoring). FEES and VFSS are considered the 2 most informative exams, allowing the identification of patients at risk for aspiration pneumonia. FEES is more practical to perform in the clinical setting given that the only material requirement is a fiberoptic laryngoscope.


Recommendation 1: for the objective investigation of OD, it is recommended to systematically perform either a FEES or VFSS, FEES being the preferred initial investigation given its increased ease of use.


There is no further mention or recommendation of the use of impedance monitoring in the assessment of dysphagia.


National Institute for Health and Care Excellence

The National Institute for Health and Care Excellence released a technology appraisal guidance on catheterless esophageal pH monitoring in 2006. This guidance indicated catheterless esophageal pH monitoring appears to be safe and effective and is commonly indicated for GERD symptoms refractory to PPIs and for GERD symptom recurrence after antireflux surgery.


In 2015, the Institute published recommendations on the diagnosis and management of GERD in children and young people. The recommendations specific to esophageal pH monitoring included:


Consider performing an esophageal pH study (or combined esophageal pH and impedance monitoring if available) in infants, children and young people with:

  • suspected recurrent aspiration pneumonia
  • unexplained apneas
  • unexplained non-epileptic seizure-like events
  • unexplained upper airway inflammation
  • dental erosion associated with a neurodisability
  • frequent otitis media
  • a possible need for fundoplication
  • a suspected diagnosis of Sandifer’s syndrome.


Consider performing an esophageal pH study without impedance monitoring in infants, children and young people if, using clinical judgement, it is thought necessary to ensure effective acid suppression.”


Prior Approval:

Not applicable



Esophageal pH monitoring (91034/91035) using a catheter-based system or catheter-free, wireless esophageal monitoring may be considered medically necessary for the following clinical indications in adults and adolescents, or children able to report symptoms:

  • Documentation of abnormal acid exposure in endoscopy-negative patients being considered for surgical anti-reflux repair; or
  • Evaluation of patients after antireflux surgery who are suspected to have ongoing abnormal reflux; or
  • Evaluation of patients with either normal or equivocal endoscopic findings and reflux symptoms that are refractory to proton pump inhibitor therapy; or
  • Evaluation of refractory reflux in patients with chest pain after cardiac evaluation and after a one month trial of proton pump inhibitor therapy; or
  • Evaluation of suspected otolaryngologic manifestations of GERD (i.e., laryngitis, pharyngitis, chronic cough) that have failed to respond to at least 4 weeks of proton pump inhibitor therapy; or
  • Evaluation of concomitant GERD in an adult-onset, nonallergic asthmatic suspected of having reflux-induced asthma as a second line


24-hour catheter-based esophageal pH monitoring may be considered medically necessary in infants or children who are unable to report or describe symptoms of reflux with at least one of the following clinical indications:

  • unexplained apnea
  • bradycardia
  • refractory coughing or wheezing, stridor, or recurrent choking (aspiration)
  • persistent or recurrent laryngitis
  • recurrent pneumonia 


The Bravo pH Monitoring System is considered investigational for evaluation in those under 4 years old, because it has not been FDA approved for use in this age group.


Esophageal pH monitoring is not medically necessary for all other indications, including, but not limited to any of the following indications because its effectiveness has not been established:

  • To detect or verify reflux esophagitis; or
  • To verify GERD with Barrett's asophagus; or
  • To evaluate “alkaline reflux”; or
  • To titrate PPI dosing or manage patients that hae already been diagnosed with GERD
  • To titrate PPI dosing in the management of Barrett's esophagus
  • As routine work-up of an individual with likely GERD, prior to refractory status


Regular use of catheter-based impedance-pH monitoring (91037/91038) is considered not medically necessary. There is not evidence that the results of testing changes treatment. Currently only a very weak recommendation exists regarding further treatment after impedance-pH testing.


Esophageal impedance in combination with pH monitoring in the evaluation of GERD is not medically necessary. Given the lack of a criterion standard, evidence supporting the use of impedance-pH testing is inconclusive. Although impedance-pH testing may increase positive tests or diagnostic yield, the potentially increased sensitivity may be accompanied by a decrease in specificity and the net effect on patient management and patient outcomes is not certain. There is a lack of comparative studies showing that impedance-pH monitoring is more useful than existing techniques to diagnose and/or treat GERD. In patients with GERD symptoms refractory to PPI therapy, 24 hour pH testing, not impedance testing, is considered the gold standard method to diagnose/confirm reflux.


At this time, the limited studies on catheter based-pH monitoring are unable to show outcomes that prove there is an overall impact on clinical management as a first line surveillance tool.


Multichannel intraluminal impedance (MII) in the evaluation of GERD, achalasia, and laryngo-pharyngeal reflux is considered not medically necessary because there is inadequate evidence in the peer-reviewed published literature proving its effectiveness in management or treatment recommendations.


Procedure Codes and Billing Guidelines:

To report provider services, use appropriate CPT* codes, Modifiers, Alpha Numeric (HCPCS level 2) codes, Revenue codes, and/or diagnosis codes;

  • 91034 Esophagus, gastroesophageal reflux test; with nasal catheter pH electrode(s) placement, recording, analysis and interpretation
  • 91035 Esophagus, gastroesophageal reflux test; with mucosal attached telemetry pH electrode placement, recording, analysis and interpretation
  • 91037 Esophageal function test, gastroesophageal reflux test with nasal catheter intraluminal impedance electrode(s) placement, recording, analysis and interpretation;
  • 91038 Esophageal function test, gastroesophageal reflux test with nasal catheter intraluminal impedance electrode(s) placement, recording, analysis and interpretation; prolonged (greater than 1 hour, up to 24 hours)


Selected References:

  • Pandolfino JE, Richter JE, Ours T, Guardino JM, Chapman J, Kahrilas PJ. Ambulatory esophageal pH monitoring using a wireless system.  Am J Gastroenterol.  2003 Apr;98(4):740-9. 
  • American Gastroenterological Association Medical Position Statement: Guidelines on the Use of Esophageal pH Recording. Gastroenterology 1996 Jun;110(6):1981
  • Ergun GA, Kahrilas PJ. Clinical applications of esophageal manometry and pH monitoring. Am J Gastroenterol 1996; 91(6):1077-89.
  • Wong WM, Bautista J, et al. Feasibility and tolerability of transnasal/per-oral placement of the wireless pH capsule vs. traditional 24-h oesophageal pH monitoring--a randomized trial. Aliment Pharmacol Ther. 2005 Jan 15;21(2):155-63.
  • Prakash C and Clouse RE. Value of extended recording time with wireless pH monitoring in evaluating gastroesophageal reflux disease. Clin Gastroenterol Hepatol. 2005 Apr;3(4):329-34.
  • Bhat YM, McGrath KM, Bielefeldt K. Wireless esophageal pH monitoring: new technique means new questions. J Clin Gastroenterol. 2006 Feb;40(2):116-21.
  • Sweis R, Fox M, Anggiansah A et al. Prolonged, wireless pH-studies have a high diagnostic yield in patients with reflux symptoms and negative 24-h catheter-based pH-studies. Neurogastroenterol Motil. 2011 Jan 16. doi:10.1111/j.1365-2982.
  • Hong SK, Vaezi MF. Gastroesophageal reflux monitoring: pH (catheter and capsule) and impedance. Gastrointest Endosc Clin N Am. 2009;19(1):1-22.
  • Hess T, Hahn EG, Konturek PC. BRAVO wireless 48 hour pH-metric system. Med Sci Monit. 2009;15(1):RA 17-RA 21.
  • Petersen RP, Pellegrini CA, Oelschlager BK. Hiatal Hernia and Gastroesophageal Reflux Disease. In: Townsend: Sabiston Textbook of Surgery, 19th ed. Saunders, an imprint of Elsevier; 2012. Chapter 44.
  • Grigolon A, Consonni D, Bravi I, et al. Diagnostic yield of 96-h wireless pH monitoring and usefulness in patients' management. Scand J Gastroenterol. 2011 May;46(5):522-30.
  • Kleiman DA, Sporn MJ, Beninato T, Metz Y, et al. Early referral for 24-h esophageal pH monitoring may prevent unnecessary treatment with acid-reducing medications. Surg endosc. 2012 Dec 12. [Epub ahead of print]
  • Koch OO, Kaindlstorfer A, Antoniou SA, Spaun G, et al. Subjective and objective data on esophageal manometry and impedance pH monitoring 1 year after endoscopic full-thickness placation for the treatment of GERD by using multiple placation implants. Gastrointest Endosc. 2013 Jan;77(1):7-14.
  • Kahrilas PJ, Shaheen NJ, Vaezi MF, Hiltz SW, Black E, Modlin IM, Johnson SP, Allen J, Brill JV, American Gastroenterological Association. American Gastroenterological Association medical position statement on the management of gastroesophageal reflux disease. Gastroenterology. 2008 Oct;135(4):1383-91.
  • Richter, JE. Con: Impedance-pH testing does not commonly alter management of GERD. The American journal of gastroenterology. 104 (11) : 2667-9, 2009. 
  • Kavitt RT, Saritas E, et al. The role of impedance monitoring in patients with extraesophageal symptoms. 2013 Oct: 123(10):2463-2468.
  • Frazzoni, M, Conigliaro, R, et al. The added value of quantitative analysis of on-therapy impedance-pH parameters in distinguishing refractory non-erosive reflux disease from functional heartburn. 2012 Feb: 24(2):141-e87.
  • Hirano I., RichterJ., et al. ACG practice guidelines: esophagela reflux testing. (Am J Gastroenterol 2007;102:668–685).
  • Katz PO, Gerson LB, Vela MF. Guidelines for the diagnosis and management of gastroesophageal reflux disease. Am J Gastroenterol 2013; 108(3):308-28.
  • Philip O. Katz MD1, Lauren B. et al. Division of Gastroenterology, Einstein Medical Center, Philadelphia, Pennsylvania, USA; Division of Gastroenterology and Hepatology, Stanford University School of Medicine, Stanford, California, USA; Division of Gastroenterology, Baylor College of Medicine & Michael E. DeBakey VA Medical Center, Houston, Texas, USA Am J Gastroenterol 2013; 108:308–328.
  • Chen IL, Gao WY, Johnson AP, et al. Proton pump inhibitor use in infants: FDA reviewer experience. J Pediatr Gastroenterol Nutr 2012; 54:8.
  • Funderburk A, Nawab U, Abraham S, et al. Temporal Association Between Reflux-like Behaviors and Gastroesophageal Reflux in Preterm and Term Infants. J Pediatr Gastroenterol Nutr 2016; 62:556
  • del Genio G, Tolone S, del Genio F, et al. Total fundoplication controls acid and nonacid reflux: evaluation by pre- and postoperative 24-h pH-multichannel intraluminal impedance. Surg Endosc 2008; 22:2518.
  • National Library of Medicine. Medical encyclopedia: Gastroesophageal reflux disease. Last update: 01/28/2016.
  • Iluyomade A, Olowoyeye A, Fadahunsi O, et al. Interference with daily activities and major adverse events during esophageal pH monitoring with bravo wireless capsule versus conventional intranasal catheter: A systematic review of randomized controlled trials. Dis Esophagus. 2016 Mar 8 [Epub ahead of print].
  • ACG, AGA, ASGE. CPT coding updates. 2016. 
  • National Institute for Health and Care Excellence (NICE). Gastro-oesophageal reflux disease in children and young people: diagnosis and management [NG1]. 2015; 
  • Kahrilas PJ, Boeckxstaens G, Smout AJ. Management of the patient with incomplete response to PPI therapy. Best Pract Res Clin Gastroenterol 2013;27:401–14.doi:10.1016/j.bpg.2013.06.005
  • Bolier EA, Kessing BF, Smout AJ, et al. Systematic review: questionnaires for assessment of gastroesophageal reflux disease. Dis Esophagus 2015;28:105–20.doi:10.1111/dote.12163
  • Cresi F, Locatelli E, Marinaccio C, et al. Prognostic values of multichannel intraluminal impedance and pH monitoring in newborns with symptoms of gastroesophageal reflux disease. The Journal of Pediatrics. 2013;162(4):770-5
  • Vardar R, Keskin M. Indications of 24-h esophageal pH monitoring, capsule pH monitoring, combined pH monitoring with multichannel impedance, esophageal manometry, radiology and scintigraphy in gastroesophageal reflux disease? Turk J Gastroenterol. 2017 Dec;28(Suppl 1):S16-S21. doi: 10.5152/tjg.2017.06.
  • Franco RA, Jr.Laryngopharyngeal reflux. UpToDate Inc., Waltham, MA. Last reviewed May 2019.
  • Kim SI, Kwon OE, Na SY, et al. Association between 24-hour combined multichannel intraluminal impedance-pH monitoring and symptoms or quality of life in patients with laryngopharyngeal reflux. Clin Otolaryngol. 2017;42(3):584-591.
  • Zifan, A, Sun, C, Gourcerol, G, Leroi, AM, and Mittal, RK. Endoflip vs high-definition manometry in the assessment of fecal incontinence: A data-driven unsupervised comparison. Neurogastroenterol Motil. 2018:e13462. PubMed: 30216661 [PMID]
  • American Academy of Otolaryngology—Head and Neck Surgery. GERD and LPR.
  • Forootan M, Zojaji H, Ehsani MJ, Darvishi M. Advances in the Diagnosis of GERD Using the Esophageal pH Monitoring, Gastro-Esophageal Impedance-pH Monitoring, And Pitfalls. Open Access Maced J Med Sci. 2018;6(10):1934–1940. Published 2018 Oct 24. doi:10.3889/oamjms.2018.410
  • Kessels SJM, Newton SS, Morona JK, et al. Safety and efficacy of wireless pH monitoring in patients suspected of gastroesophageal reflux disease: a systematic review. J Clin Gastroenterol. Oct 2017;51(9):777-788. PMID 28877081


Policy History:

  • September 2019 - Annual Review, Policy Revised
  • September 2018 - Annual Review, Policy Revised
  • September 2017 - Annual Review, Policy Revised
  • September 2016 - Annual Review, Policy Revised
  • October 2015 - Annual Review, Policy Revised
  • October 2014 - Annual Review, Policy Revised
  • January 2014 - Annual Review, Policy Revised
  • October 2013 - Interim Review, Policy Revised
  • February 2013 - Annual Review, Policy Renewed
  • February 2012 - Annual Review, Policy Revised
  • April 2011 - Annual Review, Policy Renewed

Wellmark medical policies address the complex issue of technology assessment of new and emerging treatments, devices, drugs, etc.   They are developed to assist in administering plan benefits and constitute neither offers of coverage nor medical advice. Wellmark medical policies contain only a partial, general description of plan or program benefits and do not constitute a contract. Wellmark does not provide health care services and, therefore, cannot guarantee any results or outcomes. Participating providers are independent contractors in private practice and are neither employees nor agents of Wellmark or its affiliates. Treating providers are solely responsible for medical advice and treatment of members. Our medical policies may be updated and therefore are subject to change without notice.


*CPT® is a registered trademark of the American Medical Association.