Pending Policies - Medicine


Esophageal pH Monitoring

Number:MED201.005

Effective Date:04-15-2018

Coverage:

*CAREFULLY CHECK STATE REGULATIONS AND/OR THE MEMBER CONTRACT*

Esophageal pH monitoring using a wireless or catheter-based system may be considered medically necessary for the following clinical indications in adults and children or adolescents able to report symptoms (see NOTE 1):

Documentation of abnormal acid exposure in endoscopy-negative patients being considered for surgical antireflux repair; OR

Evaluation of patients after antireflux surgery who are suspected of having ongoing abnormal reflux; OR

Evaluation of patients with either normal or equivocal endoscopic findings and reflux symptoms that are refractory to treatment with a proton pump inhibitor (PPI) at the maximum recommended dose, for at least 4 weeks; OR

Evaluation of refractory reflux in patients with chest pain after cardiac evaluation and after a 1-month trial of proton pump inhibitor therapy; OR

Evaluation of suspected otolaryngologic manifestations of gastroesophageal reflux disease (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.

NOTE 1: Esophageal pH monitoring systems should be used in accordance with FDA-approved indications and age ranges.

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:

Unexplained apnea; OR

Bradycardia; OR

Refractory coughing or wheezing, stridor, or recurrent choking (aspiration); OR

Persistent or recurrent laryngitis; OR

Recurrent pneumonia.

Catheter-based impedance-pH monitoring may be considered medically necessary in the evaluation of endoscopy-negative patients with GERD complaints refractory to PPI therapy in which documentation of non-acid reflux will alter clinical management.

Catheter-based impedance-pH monitoring is considered not medically necessary for all other indications.

Description:

Acid reflux is the cause of heartburn and acid regurgitation esophagitis, which can lead to esophageal stricture. Acid reflux can also cause or contribute to some cases of asthma, posterior laryngitis, chronic cough, dental erosions, chronic hoarseness, pharyngitis, subglottic stenosis or stricture, nocturnal choking, and recurrent pneumonia.

Background

Gastroesophageal reflux disease (GERD) is most commonly diagnosed by clinical evaluation and treated empirically with a trial of medical management. For patients who do not respond appropriately to medications, or who have recurrent chronic symptoms, endoscopy is indicated to confirm the diagnosis and assess the severity of reflux esophagitis. In some patients, endoscopy is nondiagnostic, or results are discordant with the clinical evaluation. In these cases, further diagnostic testing may be of benefit.

Esophageal monitoring is done using a tube with a pH electrode attached to its tip, which is then passed into the esophagus to almost exactly 5 cm above the upper margin of the lower esophageal sphincter. The electrode is attached to a data recorder worn on a waist belt or shoulder strap. Every instance of acid reflux, as well as its duration and pH, is recorded, over a 24-hour period. Wireless pH monitoring is achieved using endoscopic or manometric guidance to attach the pH measuring capsule to the esophageal mucosa using a clip. The capsule records pH levels for up to 96 hours and transmits them via radiofrequency telemetry to a receiver worn on the patient’s belt. Data from the recorder are uploaded to a computer for analysis by a nurse or doctor.

Another technology closely related to pH monitoring is impedance-pH monitoring, which incorporates pH monitoring with measurements 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 nonacidic.

Regulatory Status

Esophageal pH electrodes are considered class I devices by the U.S. Food and Drug Administration (FDA) and are exempt from 510(k) requirements. A catheter-free, temporarily implanted device (Bravo™ pH Monitoring System; Medtronic) was cleared for marketing by the FDA through the 510(k) process for the purpose of “gastroesophageal pH measurement and monitoring of gastric reflux in adults and children from 4 years of age.”

A number of wireless and catheter-based (wired) esophageal pH monitoring devices have been cleared for marketing by the FDA through the 510(k) process. Examples include the Bravo pH Monitoring System (Given Imaging), the Sandhill Scientific PediaTec™ pH Probe (Sandhill Scientific), the ORION II Ambulatory pH Recorder (MMS, Medical Measurement Systems) and the TRIP CIC Catheter (Tonometrics). FDA product code: FFT.

Rationale:

This policy was originally created in 1990 and was updated regularly with searches of the MEDLINE database. The most recent literature search was performed through October 14, 2016. The following is a summary of the key literature.

Evaluation of a diagnostic technology typically focuses on the following 3 parameters: (1) analytic validity; (2) clinical validity or diagnostic parameters (sensitivity, specificity, positive and negative predictive value) in different populations of patients; and (3) clinical utility (demonstration that the diagnostic information can be used to improve patient outcomes.

Analytic Validity

We did not identify any literature assessing the analytic validity of esophageal pH monitoring.

Clinical Validity

Esophageal pH Monitoring Using Catheter-Based Systems

Esophageal pH monitoring for 24 hours using catheter-based systems is primarily used in patients who have gastroesophageal reflux disease (GERD) that has not responded symptomatically to a program of medical therapy (including proton pump inhibitors [PPIs]) or in patients with refractory extra-esophageal symptoms). Although established technology, aspects of these systems’ use as a diagnostic test for GERD are problematic and thus make it difficult to determine its utility, or the utility of potential alternative tests.

There is no independent reference standard for GERD for specific populations. Traditional pH monitoring has been evaluated in patients with endoscopically diagnosed GERD, where it has been shown to be positive 77% to 100% of the time. (1) However, in clinically defined but endoscopically negative patients, the test is positive from 0% to 71% of the time. In normal control populations, traditional pH monitoring is positive in 0% to 15% of subjects. Thus the test is imperfectly sensitive and specific in patients with known presence or absence of disease. The state of this evidence regarding the diagnostic capability of catheter-based pH monitoring led the authors of this technical review “…to conclude that ambulatory pH studies quantify esophageal acid exposure but that this has an imperfect correlation with reflux-related symptoms, esophageal sensitivity, or response to acid suppressive therapy.” (1)

Without a reference standard for GERD, it is difficult to compare the diagnostic test performance of different types of tests. It is possible to determine the degree to which 2 tests correlate with each other but difficult to determine if 1 test is better.

Wireless pH Monitoring

Several observations of relevance to this Policy are based on a 2006 Blue Cross Blue Shield Association (BCBSA) Technology Evaluation Center (TEC) Special Report on wireless esophageal pH monitoring. (2) Six case series reviewed in the report demonstrated success rates over 90% in completing a 48-hour pH study. Two studies that surveyed patients who received wireless pH monitoring and patients who received traditional catheter monitoring showed less discomfort, less disruption of daily activities, and higher overall satisfaction with the wireless test. Studies that evaluated test positivity in clinically diagnosed GERD cases and normal controls showed similar results as have been reported in such patients using traditional pH monitoring. Studies that directly compared the performance of traditional catheter and wireless pH monitoring in the same patients showed fairly close correlation between the 2 types of studies after correcting for calibration differences. However, the ideal cut-point for test positivity differed for the tests.

Some studies have attempted to support an argument that a longer monitoring time with a wireless monitor results in superior test performance. However, without a reference standard, or showing superior patient outcomes based on the longer test, such an argument cannot be made. The longer monitoring period usually results in a larger proportion of tests that are classified as positive, depending on the method of determining a positive test. Prakash and Clouse compared the diagnostic yield for a single day of monitoring with the complete 2 days of monitoring. (3) They reported that the second day of recording time increased the proportion of subjects with symptoms by 6.8%. However, this study had several methodologic flaws. Ideally, a study that compares the diagnostic performance of an additional day of monitoring would require an independent reference standard or demonstration of improved patient outcomes when managing patients with a 1-day versus a 2-day study. In this study, the 2-day study was essentially considered the “reference test,” and there was no discussion of how the second day of monitoring was used to improve patient management in this heterogeneous group of patients. In addition, in their statistical analysis, the authors eliminated patients who did not report any symptoms during the testing period, thus deflating the denominator and inflating the yield of the additional day of testing. Finally, the 1-day test was essentially a component of the 2-day test, and thus the 2 monitoring periods were not independent, further limiting any comparison between them. A greater number of positive tests produced by a longer duration of test is not evidence of a superior test.

Studies published since the 2006 TEC Special Report have shown similar findings on the correlation between wireless pH monitoring and standard catheter monitoring. Wenner et al., in a study of 64 patients with GERD and 50 asymptomatic controls, showed a sensitivity of 59% to 65%, when setting the specificity to 90% to 95%. (4) The sensitivity of wireless monitoring was noted to be worse than other studies of traditional pH monitoring, but the patient population may have had less severe disease. A study by Schneider et al. showed similar diagnostic performance of wireless and traditional pH monitoring. (5) Hakanson et al. evaluated simultaneous wireless and traditional pH testing in 92 patients. (6) Wireless pH testing showed consistently lower estimates of acid exposure than traditional pH testing. The 2 techniques correlated (r2=0.66); however, the range between limits of agreement was wide. The techniques were concordant on the final diagnosis 82.1% of the time.

Additional studies have replicated findings that a longer period of monitoring increases the proportion of positive tests. Scarpulla et al. attempted 96-hour monitoring in 83 patients. (7) Monitoring for the full 96 hours was successful in 41% of patients. In them, the proportion showing some degree of pathologic acid exposure increased as monitoring time increased. Garrean et al. studied the use of 96-hour pH testing where during the first 2 days of monitoring, patients were off therapy, and during the second 2 days, the patients were prescribed PPIs. (8) As expected, during the second and third days, fewer patients showed reflux symptoms. It is difficult to determine from data analsis how such a testing protocol improves the diagnosis of GERD. Grigolon et al. showed that in 51 patients receiving prolonged monitoring, the 96-hour test reduced the number of indeterminate tests from 11 to 5. (9) In this particular study, comparison of outcomes for patients who received wireless monitoring and a matched control group who received traditional catheter monitoring showed similar outcome and satisfaction.

Impedance-pH Testing

Evidence on the use of impedance pH testing suffers from similar issues as the evaluation of wireless pH testing: lack of a reference standard, and lack of evidence that shows improved patient outcomes. Many studies have argued that an increase in positive tests, or diagnostic yield, is by itself evidence that supports the validity of the test. However, the increase in positive tests, if it indicates increased sensitivity, may decrease specificity. The net effect on patient management and patient outcomes is uncertain.

Several studies have demonstrated a higher yield for positive tests when using impedance-pH testing and identifying reflux events that are non- or only weakly acidic (and thus would not be detected using pH testing alone). (10-12) Bajbouj et al. studied 41 patients with atypical GERD symptoms with numerous tests. (10) The test that produced the highest number of positive findings was impedance pH testing. Bredenoord et al. did a similar study in 48 patients. (11) A higher proportion of subjects had positive tests when using impedance-pH data than when using pH data (77%) than when using pH data alone (67%). A study by Mainie et al. showed similar findings. (12)

Studies have examined performing impedance-pH testing while patients are on acid suppression therapy. Vela et al. demonstrated that during acid suppressive therapy, the total number of reflux episodes is similar, but fewer episodes of acidic reflux occur. (13)

Although impedance-pH testing produces a higher number of positive tests, particularly compared with traditional or wired pH testing in the setting of concurrent acid suppressive therapy, there is insufficient evidence that these test results are more accurate.

Section Summary: Clinical Validity

The tests under consideration all correlate with symptoms of GERD or endoscopically defined GERD. However, without a true reference standard for clinical GERD, the diagnostic characteristics of catheter- based pH monitoring, wireless pH monitoring, and impedance-pH testing are uncertain.

Clinical Utility

Clinical utility of pH testing can be determined by studies that directly compare strategies of diagnosis and treatment with pH testing to strategies of diagnosis and treatment without pH testing, or by a compelling indirect chain of evidence that supports improved outcomes with the use of pH testing. No studies were identified that evaluated the clinical utility of any of the tests. The indirect chain of evidence supporting its use has not been clearly formulated and argued.

Summary of Evidence

For individuals who have gastroesophageal reflux disease (GERD) who receive catheter-based pH monitoring, the evidence includes various cross-sectional studies in different populations evaluating test performance. Relevant outcomes include test accuracy and validity, symptoms, and functional outcomes. Positive pH monitoring tests correlate with endoscopically defined GERD and with GERD symptoms, but because there is no reference standard for clinical GERD, diagnostic characteristics cannot be determined. There are no studies of clinical utility showing improved outcomes, and the indirect chain of evidence supporting the utility of the test is weak. The evidence is insufficient to determine that the technology improves health outcomes.

For individuals who have GERD who receive wireless pH monitoring, the evidence includes various cross-sectional studies in different populations evaluating test performance and diagnostic yield. Relevant outcomes include test accuracy and validity, symptoms, and functional outcomes. Positive wireless pH monitoring tests correlate with endoscopically defined GERD and with GERD symptoms, but because there is no reference standard for clinical GERD, diagnostic characteristics cannot be determined. Some studies have shown higher positive test rates with prolonged wireless monitoring compared to catheter- based pH monitoring, but the effect of this finding on patient outcomes is uncertain. There are no studies of clinical utility showing improved outcomes, and the indirect chain of evidence supporting the utility of the test is weak. The evidence is insufficient to determine that the technology improves health outcomes.

For individuals who have GERD who receive impedance pH testing, the evidence includes various cross- sectional studies in different populations evaluating test performance and diagnostic yield. Relevant outcomes include test accuracy and validity, symptoms, and functional outcomes. Positive impedance pH tests correlate with endoscopically defined GERD and with GERD symptoms, but because there is no reference standard for clinical GERD, diagnostic characteristics cannot be determined. Some studies have shown higher positive test rates with impedance pH testing compared to pH testing alone, but the effect of this finding on patient outcomes is uncertain. There are no studies of clinical utility showing improved outcomes, and the indirect chain of evidence supporting utility of the test is weak. The evidence is insufficient to determine that the technology improves health outcomes.

Practice Guidelines and Position Statements

American College of Gastroenterology

The American College of Gastroenterology (ACG) released practice guidelines on esophageal reflux testing in 2007. (14) The literature up to 2006 was reviewed. Although the literature on wireless pH testing was extensively reviewed, the recommendations for testing made no distinction between wireless and traditional pH monitoring. An indirect endorsement of wireless monitoring might be inferred from a statement that says that a 48-hour study would produce a greater diagnostic yield from a symptom association test. Symptom-association tests require statistical testing of the data, and a 48-hour test produces more data points. However, these statistical correlation tests are not perfect, because the guidelines state that such measures “do not ensure a response to either medical or surgical antireflux therapies.” No studies were cited that indicated superior outcomes for patients for treatment guided by wireless pH testing versus traditional pH testing. The major advantage for the wireless system cited was patient tolerability.

Impedance pH monitoring was cited as “may be useful” (a lower category of recommendation than for pH monitoring) for evaluation of patients with insufficient response to medical therapy in whom documentation of nonacid reflux would alter clinical management. It was suggested that impedance monitoring has a greater yield for findings than pH monitoring when performed on proton pump inhibitor (PPI) therapy. The last statement of the guideline states that implications of an abnormal impedance test are unproven at this time.

In 2013, the ACG published guidelines on the diagnosis and management of GERD. (15) The guidelines stated “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 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 note there is limited evidence and lack of clear consensus on how testing should be performed (e.g., catheter-based pH, wireless pH, or impedance-pH) for refractory GERD.

American Gastroenterological Association

The American Gastroenterological Association released a medical position statement and accompanying technical review on the management of GERD in 2008. (16) Ambulatory impedance pH, catheter pH, and wireless pH monitoring were all supported as methods to evaluate patients with suspected GERD with otherwise normal endoscopy and no response to PPI therapy. The guidelines had a “grade B” recommendation, denoting fair evidence that the practice improves health outcomes. The guidelines additionally states that the wireless pH monitor has superior sensitivity to catheter pH monitoring because of the extended period of recording.

However, as noted previously, an increase in positive tests has been documented in other reports as producing both increased sensitivity and decreased specificity relative to the reference standard used in the particular study. Thus, taking into account both characteristics of diagnostic performance, it is unknown as to whether patient outcomes are improved.

National Institute for Health and Care Excellence

The National Institute for Health and Care Excellence released technology appraisal guidance on

catheterless esophageal pH monitoring in July 2006. (17) This guidance indicates 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.

Ongoing and Unpublished Clinical Trials

A search of ClinicalTrials.gov in October 2016 did not identify any ongoing or unpublished trials that would likely influence this policy.

Contract:

Each benefit plan, summary plan description or contract defines which services are covered, which services are excluded, and which services are subject to dollar caps or other limitations, conditions or exclusions. Members and their providers have the responsibility for consulting the member's benefit plan, summary plan description or contract to determine if there are any exclusions or other benefit limitations applicable to this service or supply. If there is a discrepancy between a Medical Policy and a member's benefit plan, summary plan description or contract, the benefit plan, summary plan description or contract will govern.

Coding:

CODING:

Disclaimer for coding information on Medical Policies

Procedure and diagnosis codes on Medical Policy documents are included only as a general reference tool for each policy. They may not be all-inclusive.

The presence or absence of procedure, service, supply, device or diagnosis codes in a Medical Policy document has no relevance for determination of benefit coverage for members or reimbursement for providers. Only the written coverage position in a medical policy should be used for such determinations.

Benefit coverage determinations based on written Medical Policy coverage positions must include review of the member’s benefit contract or Summary Plan Description (SPD) for defined coverage vs. non-coverage, benefit exclusions, and benefit limitations such as dollar or duration caps.

CPT/HCPCS/ICD-9/ICD-10 Codes

The following codes may be applicable to this Medical policy and may not be all inclusive.

CPT Codes

91034, 91035, 91037, 91038

HCPCS Codes

None

ICD-9 Diagnosis Codes

Refer to the ICD-9-CM manual

ICD-9 Procedure Codes

Refer to the ICD-9-CM manual

ICD-10 Diagnosis Codes

Refer to the ICD-10-CM manual

ICD-10 Procedure Codes

Refer to the ICD-10-CM manual


Medicare Coverage:

The information contained in this section is for informational purposes only. HCSC makes no representation as to the accuracy of this information. It is not to be used for claims adjudication for HCSC Plans.

The Centers for Medicare and Medicaid Services (CMS) does not have a national Medicare coverage position. Coverage may be subject to local carrier discretion.

A national coverage position for Medicare may have been developed since this medical policy document was written. See Medicare's National Coverage at <http://www.cms.hhs.gov>.

References:

1. Kahrilas PJ, Quigley EM. Clinical esophageal pH recording: a technical review for practice guideline development. Gastroenterology. Jun 1996; 110(6):1982-1996. PMID 8964428

2. Blue Cross and Blue Shield Association Technology Evaluation Center (TEC). Chicago, Illinois. Special Report: Wireless pH Monitoring. TEC Assessments. 2006; 21(2).

3. Prakash C, Clouse RE. Value of extended recording time with wireless pH monitoring in evaluating gastroesophageal reflux disease. Clin Gastroenterol Hepatol. Apr 2005; 3(4):329-334. PMID 15822037

4. Wenner J, Johansson J, Johnsson F, et al. Optimal thresholds and discriminatory power of 48-h wireless esophageal pH monitoring in the diagnosis of GERD. Am J Gastroenterol. Sep 2007; 102(9):1862-1869. PMID 17509034

5. Schneider JH, Kramer KM, Konigsrainer A, et al. Ambulatory pH: monitoring with a wireless system. Surg Endosc. Nov 2007; 21(11):2076-2080. PMID 17484003

6. Hakanson BS, Berggren P, Granqvist S, et al. Comparison of wireless 48-h (Bravo) versus traditional ambulatory 24-h esophageal pH monitoring. Scand J Gastroenterol. 2009; 44(3):276-283. PMID 19040176

7. Scarpulla G, Camilleri S, Galante P, et al. The impact of prolonged pH measurements on the diagnosis of gastroesophageal reflux disease: 4-day wireless pH studies. Am J Gastroenterol. Dec 2007; 102(12):2642-2647. PMID 17850412

8. Garrean CP, Zhang Q, Gonsalves N, et al. Acid reflux detection and symptom-reflux association using 4-day wireless pH recording combining 48-hour periods off and on PPI therapy. Am J Gastroenterol. Jul 2008; 103(7):1631-1637. PMID 18557714

9. Grigolon A, Consonni D, Bravi I, et al. Diagnostic yield of 96-h wireless pH monitoring and usefulness in patients' management. Scand J Gastroenterol. May 2011; 46(5):522-530. PMID 21366495

10. Bajbouj M, Becker V, Neuber M, et al. Combined pH-metry/impedance monitoring increases the diagnostic yield in patients with atypical gastroesophageal reflux symptoms. Digestion. 2007; 76(3-4):223-228. PMID 18174685

11. Bredenoord AJ, Weusten BL, Timmer R, et al. Addition of esophageal impedance monitoring to pH monitoring increases the yield of symptom association analysis in patients off PPI therapy. Am J Gastroenterol. Mar 2006; 101(3):453-459. PMID 16464226

12. Mainie I, Tutuian R, Shay S, et al. Acid and non-acid reflux in patients with persistent symptoms despite acid suppressive therapy: a multicentre study using combined ambulatory impedance-pH monitoring. Gut. Oct 2006; 55(10):1398-1402. PMID 16556669

13. Vela MF, Camacho-Lobato L, Srinivasan R, et al. Simultaneous intraesophageal impedance and pH measurement of acid and nonacid gastroesophageal reflux: effect of omeprazole. Gastroenterology. Jun 2001; 120(7):1599-1606. PMID 11375942

14. Hirano I, Richter JE. ACG practice guidelines: esophageal reflux testing. Am J Gastroenterol. Mar 2007; 102(3):668-685. PMID 17335450

15. Katz PO, Gerson LB, Vela MF. Guidelines for the diagnosis and management of gastroesophageal reflux disease. Am J Gastroenterol. Mar 2013; 108(3):308-328; quiz 329. PMID 23419381

16. Kahrilas PJ, Shaheen NJ, Vaezi MF, et al. American Gastroenterological Association Medical Position Statement on the management of gastroesophageal reflux disease. Gastroenterology. Oct 2008; 135(4):1383-1391, 1391 e1381-1385. PMID 18789939

17. National Institute for Health and Care Excellence (NICE). Catheterless esophageal pH monitoring (IPG187). 2006; Available at: <http://publications.nice.org.uk.> (accessed 2016 October).

18. Esophageal pH Monitoring. Chicago, Illinois: Blue Cross Blue Shield Association Medical Policy Reference Manual (November 2016) Medicine 2.01.20.

Policy History:

Date Reason
4/15/2018 Reviewed. No changes.
8/1/2017 Document updated with literature review. Coverage unchanged.
10/1/2016 Reviewed. No changes.
2/1/2016 Document updated with literature review. The following was added to Coverage: treatment with a proton pump inhibitor (PPI) at the maximum recommended dose, for at least 4 weeks was added to the third bullet under the following statement: Esophageal pH monitoring using a wireless or catheter-based system may be considered medically necessary for the following clinical indications in adults and children or adolescents able to report symptoms*. The title was changed from Esophageal Monitoring.
2/1/2014 Document updated with literature review. The following were removed from coverage section: 1) 4 week requirement of proton pump inhibitor therapy previously required for “evaluation of concomitant GERD in an adult-onset, nonallergic asthmatic suspected of having reflux-induced asthma” and 2) evaluation of the contraction of the muscles in the esophagus to establish motility. The following was added to the coverage section: 1) Catheter-based impedance-pH monitoring may be considered medically necessary in the evaluation of endoscopy-negative patients with GERD complaints refractory to PPI therapy in which documentation of non-acid reflux will alter clinical management 2) Catheter-based impedance-pH monitoring is considered not medically necessary for all other indications and 3) *Esophageal pH monitoring systems should be used in accordance with FDA-approved indications and age ranges.
11/1/2008 Editorial revision
4/15/2008 Policy reviewed without literature review; new review date only. This policy is no longer scheduled for routine literature review and update.
6/1/2007 Coverage revised
11/1/2006 Revised/updated entire document
10/24/2006 Revised/updated entire document
5/1/1996 Revised/updated entire document
3/1/1995 Revised/updated entire document
12/1/1990 New medical document

Archived Document(s):

Title:Effective Date:End Date:
Esophageal pH Monitoring04-15-201804-14-2019
Esophageal pH Monitoring08-01-201704-14-2018
Esophageal pH Monitoring10-01-201607-31-2017
Esophageal pH Monitoring02-01-201609-30-2016
Esophageal Monitoring02-01-201401-31-2016
Esophageal Monitoring11-01-200801-31-2014
Esophageal pH Monitoring04-15-200810-31-2008
Esophageal pH Monitoring06-01-200704-14-2008
Esophageal pH Monitoring11-01-200605-31-2007
Esophageal pH Monitoring10-24-200310-31-2006
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