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Ambulatory Esophageal pH Monitoring

» Summary» Procedure Codes
» Description» Selected References
» Prior Approval» Policy History
» Policy

Medical Policy: 02.01.03 
Original Effective Date: September 2004 
Reviewed: October 2014 
Revised: October 2014 

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.


Gastroesophageal reflux disease (GERD) is usually diagnosed by clinical history and endoscopy, and is treated empirically with a trial of medical management, of at least four weeks, 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. 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

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 are unproven at this time.


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 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.


Prior Approval: 


Not applicable



Esophageal pH monitoring 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 antireflux repair 
  • Evaluation of patients after antireflux surgery who are suspected to have ongoing abnormal reflux
  • Evaluation of patients with either normal or equivocal endoscopic findings and reflux symptoms that are refractory to proton pump inhibitor therapy
  • Evaluation of refractory reflux in patients with chest pain after cardiac evaluation and after a one month trial of proton pump inhibitor therapy
  • 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
  • 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 

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 evaluate “alkaline reflux”; or
  • To titrate PPI dosing in the management of Barrett's esophagus.

Regular use of catheter-based impedance-pH monitoring is considered not medically necessary.


Esophageal impedance in combination with pH monitoring in the evaluation of GERD is considered not medically necessary because there is inadequate evidence in the peer-reviewed published clinical literature regarding its effectiveness.


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.


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 is considered the gold standard method to diagnose/confirm reflux.


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.


Policy History: 


Date                                        Reason                               Action

April 2011                              Annual review                     Policy renewed

February 2012                        Annual review                     Policy revised

February 2013                        Annual review                     Policy renewed

October 2013                         Interim review                     Policy revised

January 2014                         Annual review                     Policy revised

October 2014                         Annual review                     Policy revised


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.

*Current Procedural Terminology © 2012 American Medical Association. All Rights Reserved.

Contact Information
New information or technology that would be relevant for Wellmark to consider when this policy is next reviewed may be submitted to:
  Wellmark Blue Cross and Blue Shield
  Medical Policy Analyst
  P.O. Box 9232
  Des Moines, IA 50306-9232
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