| Medical Policy |
| Subject: Mucosal Integrity Testing | |
| Document #: MED.00166 | Publish Date: 07/01/2026 |
| Status: New | Last Review Date: 05/14/2026 |
| Description/Scope |
This document addresses the use of mucosal integrity testing (for example, the MiVuTM Mucosal Integrity Testing System, Diversatek, Inc., Milwaukee, WI), which has been proposed as a diagnostic aid to support the evaluation of gastroesophageal reflux disease (GERD) and non-GERD conditions such as eosinophilic esophagitis (EoE) during an endoscopy. The device incorporates three impedance sensors on a tubular tip that fits over the distal end of an endoscope and is placed in contact with the esophageal lining. It is designed to measure and analyze the electrical impedance of esophageal tissue. The system then displays real-time impedance measurements, mucosal integrity contour patterns, and the likelihood of GERD, non-GERD, and EoE on a computer monitor. Mucosal integrity testing is also referred to as mucosal impedance testing (MIT).
Note: For more information, please see the following related documents.
Note: For a high-level overview of this document, please see “Summary for Members and Families” below.
| Position Statement |
Investigational and Not Medically Necessary:
The use of mucosal integrity testing is considered investigational and not medically necessary for all indications.
| Summary for Members and Families |
This document describes clinical studies and expert recommendations, and explains whether mucosal integrity testing is clinically appropriate. The following summary does not replace the medical necessity criteria or other information in this document. The summary may not contain all the relevant criteria or information. This summary is not medical advice. Please check with your healthcare provider for any advice about your health.
Key Information
Mucosal integrity testing, also called mucosal impedance testing (MIT), is done during an upper endoscopy. A small device is placed on the end of the camera to touch the lining of the esophagus. It measures how well the lining works as a barrier by checking electrical signals in the tissue. Doctors may use these patterns to help tell the difference between conditions such as gastroesophageal reflux disease (GERD) and non-GERD conditions such as eosinophilic esophagitis (EoE). This test gives results right away during the procedure.
What the Studies Show
This test works by measuring how easily electricity passes through the lining of the esophagus. Damaged or inflamed tissue changes these measurements. Some studies show that different diseases have different patterns. For example, reflux disease may affect the lower esophagus more, while EoE may affect the whole esophagus. Some studies also show that the numbers may improve after treatment, which suggests the test could help track progress.
However, most studies have been small and done at a single center. Results across studies have not been consistent, and there are no clear standards for what the tests results mean. Some studies show only moderate accuracy, and there can be overlap in test results between conditions making proper identification difficult. Measurements can also be affected by how the device is placed or by fluid in the esophagus. Medical groups such as the American College of Gastroenterology (ACG) and the American Society for Gastrointestinal Endoscopy (ASGE) do not recommend this test for routine use. They continue to support standard methods such as symptom review, endoscopy, and reflux monitoring. Larger and better studies are needed to know if this test improves health outcomes.
Is this Clinically Appropriate?
This test is not clinically appropriate because it has not been proven to improve health.
Studies suggest the test may help identify disease patterns, but the research has important limits. Many studies include small groups of people and use different methods, which makes results hard to compare. There is also no clear agreement on normal or abnormal values. Some studies show only moderate accuracy, and results can overlap between conditions. Because of this, doctors cannot rely on the test alone to make decisions.
Unnecessary or unproven tests can lead to treatment that does not help. More high-quality studies with larger groups are needed to confirm that this test is accurate, reliable, and helpful in guiding care. Mucosal integrity testing is not clinically appropriate for any indication.
| Rationale |
Summary
This document addresses mucosal integrity (impedance) testing, including the MiVu system, as an endoscopy-based technique intended to assess esophageal mucosal integrity and assist in the evaluation of gastroesophageal reflux disease (GERD) and non-GERD conditions such as eosinophilic esophagitis (EoE) using real-time impedance measurements and pattern recognition. While early studies suggest the technology can identify characteristic disease patterns and may have potential for diagnostic support and treatment monitoring, the overall evidence base is limited, with small, heterogeneous studies, variable thresholds, and ongoing uncertainty regarding accuracy, reproducibility, and clinical impact. Current gastroenterology society guidance (for example, the American College of Gastroenterology [ACG] and the American Society for Gastrointestinal Endoscopy [ASGE]) emphasizes established diagnostic approaches such as symptom assessment, endoscopy, and reflux monitoring, and does not currently recommend mucosal integrity testing for routine clinical use.
Discussion
A prospective observational study (van Hoeij, 2016) evaluated regional differences in acid sensitivity and mucosal integrity in the esophagus of 12 individuals with GERD using acid perfusion testing, impedance measurements, and biopsy-based analyses. The study found that the proximal esophagus is more sensitive to acid exposure, demonstrated by a shorter time to symptom perception (0.8 vs. 3.9 minutes), despite having relatively preserved mucosal integrity compared to the distal esophagus, where impedance was lower and permeability higher, indicating greater barrier impairment. These findings suggest that heightened symptom perception from proximal reflux is not driven by increased mucosal damage but may instead reflect differences in sensory mechanisms or neural distribution. Limitations include a small sample size, single-center design, and highly selected population with confirmed GERD, which may limit generalizability. The experimental acid perfusion model may not fully replicate physiologic reflux conditions, and variations in exposure area between proximal and distal segments could confound results. Additionally, some measurements (for example, intercellular space ratios) did not show significant differences, and allowance of rescue antacid use may have influenced mucosal findings. Overall, while the study provides mechanistic insight, further larger and more representative studies are needed to confirm these observations and clarify their clinical implications.
Scientific Studies
A study by Choksi (2018) evaluated whether esophageal mucosal impedance (MI) patterns measured during endoscopy can distinguish EoE from GERD and non-GERD conditions. In a retrospective discovery cohort (n=91) and a prospective validation cohort (n=49), the author found that EoE demonstrates a distinct pattern of uniformly low impedance along the esophagus, whereas GERD shows low distal values with proximal normalization. These patterns enabled differentiation with moderate diagnostic accuracy using individual measurements and very high accuracy when interpreting the overall pattern (up to 100% sensitivity and 96% specificity in the validation cohort). The findings suggest that MI can provide real-time assessment of epithelial integrity during endoscopy and may reduce reliance on biopsies for diagnosis and monitoring. Limitations include the small sample size and single-center design, as well as reliance on retrospective data for the discovery cohort. Measurement variability may occur due to manual probe positioning and potential interference from intraluminal contents, and the device used only a single sensing channel. The study included limited numbers of certain subgroups, and did not fully evaluate overlap conditions such as concurrent GERD and EoE. Additionally, diagnostic thresholds and patterns require further validation in larger, diverse populations before widespread clinical adoption.
A prospective comparative study (Lowry, 2018) evaluated MI as a tool to assess disease activity in pediatric EoE by comparing impedance measurements with histologic findings across active EoE, inactive EoE, nonerosive reflux disease, and controls. There were 127 pediatric participants aged 1-18 years old included in the study (32 with active EoE, 10 with inactive EoE, 32 with nonerosive reflux disease [NERD] and 53 in the control group), The study found that MI values were significantly lower in active EoE at all esophageal levels (median 1069, 1368, and 1707 ohms at 2, 5, and 10 cm, respectively) compared to inactive EoE (3663, 3657, 4494), NERD (2754, 3243, 4387), and controls (3091, 3760, 4509) (p<0.001) for all comparisons to individuals with active EoE). MI showed a strong inverse correlation with disease severity, with higher eosinophil counts and spongiosis associated with lower impedance (p<0.001), indicating that MI reflects mucosal inflammation. Regression analysis showed that each 1000-ohm decrease in MI increased the odds of higher eosinophil counts by 117% (p<0.001) and more severe spongiosis by 87% (p<0.001). Diagnostic performance varied by location in predicting active EoE from inactive EoE, with sensitivity/specificity of 69%/100% (2 cm), 78%/90% (5 cm), and 66%/100% (10 cm), and receiver operating curve (ROC) areas of 0.90, 0.86, and 0.88, respectively. Active EoE demonstrated consistently lower impedance values compared to other groups. These findings suggest that MI may provide rapid, real-time assessment of disease activity during endoscopy and has potential as a less invasive alternative to repeated biopsies for monitoring. Limitations include the cross-sectional design, which limits causal inference, and a heterogeneous pediatric population with incomplete confirmatory testing (for example, limited pH-impedance data in some groups). Measurement variability may occur due to technical factors such as probe contact or intraluminal air/fluid, and some overlap in impedance values between groups was observed. Additionally, the study did not assess correlation with symptoms, and the need for endoscopic placement still limits its noninvasive potential. Larger, prospective studies are needed to validate thresholds, improve standardization, and determine its role in clinical practice. Of note in the U.S. Food and Drug Administration (FDA) De Novo summary DEN180067 for the MI Test System, the FDA states “in this De Novo request, existing clinical information was not leveraged to support the use of the device in pediatric patient population.”
Patel (2019) conducted a multicenter prospective study that evaluated a balloon-based MI system used during endoscopy to assess esophageal mucosal integrity and distinguish GERD, EoE, and non-GERD conditions. Of the 69 individuals included in the study, 24 were categorized as having GERD, 21 with EoE, and 24 with non-GERD. The study found that each condition demonstrated a distinct impedance pattern along the esophagus, non-GERD showed consistently higher values, GERD showed low distal values with proximal normalization, and EoE showed low values throughout, allowing differentiation using contour patterns and derived metrics (intercept and slope) with moderate-to-high diagnostic accuracy (area under the receiver operating characteristic curve [AUC] 0.69 for GERD, 0.89 for EoE, and 0.84 for non-GERD), while channel-level comparisons also showed significantly lower impedance in GERD and EoE versus non-GERD across all esophageal segments (p<0.01)), which was also validated externally. Limitations include a small sample size and model constraints that assume mutually exclusive diagnoses and equal disease prevalence, which may not reflect real-world populations. The model also does not incorporate clinical variables that could influence diagnostic probability, and its use is limited in certain groups, such as those with severe fibrostenotic disease or unstudied motility disorders. Further large-scale and outcomes-based studies are needed to confirm reliability, generalizability, and impact on clinical decision-making.
In a prospective study, Mutha (2022) evaluated whether probe-based confocal laser endomicroscopy (pCLE) and mucosal integrity testing performed during upper endoscopy could assess esophageal epithelial barrier function (EBF) and differentiate GERD from non-GERD conditions. Among 54 participants, GERD (n=28 and non-GERD (n=26), pCLE did not distinguish GERD from non-GERD and showed no meaningful correlation with in vitro measures of permeability. In contrast, mucosal integrity testing (MIT) demonstrated lower MI values in GERD and an inverse relationship with permeability, suggesting it may better reflect impaired barrier function. Sensitivity and specificity of identifying GERD with MIT was 76% and 72% respectively. Limitations include a small sample size that was derived from a single center. There was substantial overlap in impedance values between groups; correlations with permeability were not statistically significant; and reliance on surrogate measures (for example, pH testing and biopsy-based permeability) may not fully capture GERD pathophysiology. Additionally, technical factors related to biopsy handling and measurement methods, as well as heterogeneity in populations, may limit generalizability and clinical applicability.
Review Articles
In 2017, Vaezi published a technical review describing MI as a novel endoscopic technique that directly measures esophageal epithelial conductivity to assess mucosal integrity and improve diagnosis of GERD and other esophageal disorders. Unlike traditional potential of pH or impedance-pH monitoring, MI provides rapid, real-time assessment during endoscopy and may reflect the cumulative effects of chronic reflux exposure. Studies summarized in the article demonstrate that MI can differentiate GERD from non-GERD conditions and EoE based on characteristic impedance patterns along the esophagus, shows higher specificity and positive predictive value than pH testing, and may also be useful for monitoring treatment response to therapy, as impedance values change to indicate improvement. Limitations include that the evidence is based on early, single-center studies with relatively small cohorts and requires broader validation. Diagnostic thresholds and standardized protocols are not fully established, and comparisons to existing modalities are limited by methodological variability. The authors noted that while MI offers advantages in comfort and efficiency, its clinical role is still evolving, particularly in complex scenarios such as extraesophageal symptoms or surgical decision-making. Additionally, potential conflicts of interest and the investigational nature of technology highlight the need for larger, independent, prospective studies to confirm accuracy, reproducibility, and impact on clinical outcomes.
Barrett (2018) presented a review article describing MI as an emerging endoscopic technique that measures esophageal epithelial integrity in real time and may improve the diagnosis and management of GERD and EoE. MI testing provides rapid measurements during endoscopy and reflects chronic mucosal injury rather than transient reflux events, with studies demonstrating distinct impedance patterns that differentiate GERD (low distal values with proximal increase) from EoE (low values throughout the esophagus). MI has also shown utility in monitoring treatment response, correlating with histologic changes such as dilated intercellular spaces and eosinophilia, and may aid in evaluating extraesophageal symptoms and guiding therapy. Limitations include that much of the supporting evidence comes from relatively small, single-center or early-phase studies, and diagnostic thresholds and standardized protocols are not yet fully established. Reported sensitivity and specificity are comparable to existing modalities rather than clearly superior, and clinical adoption may be limited by variability in measurement technique and need for operator expertise. Additionally, overlap in histologic and clinical features between GERD and EoE can still complicate interpretation, and further large, prospective studies are needed to validate its role, particularly in predicting outcomes or replacing established diagnostic approaches.
Lei (2019) reported on a review describing mucosal impedance testing (MIT) as a novel endoscopic technique that measures esophageal epithelial conductivity to assess mucosal integrity and improve the diagnosis and management of GERD and related disorders. MIT provides rapid, real-time measurements during endoscopy and reflects chronic mucosal changes rather than transient reflux events, with studies showing it can differentiate GERD from non-GERD conditions and EoE based on characteristic impedance patterns along the esophagus. It also demonstrates potential for monitoring treatment response, as impedance values normalize with effective therapy, and may help guide management in complex or refractory cases. However, limitations include that the evidence base is still evolving, with many studies conducted in small or selected populations and variability in diagnostic thresholds and measurement techniques. While MIT shows higher specificity than some traditional tests, its sensitivity and role relative to established modalities such as pH-impedance monitoring are not fully defined. There is also inconsistent correlation with histologic markers in certain conditions (for example, EoE), and its clinical utility in broader populations, including those with extraesophageal symptoms or refractory disease, requires further validation through larger, prospective studies.
Dao (2024) wrote a review article summarizing emerging endoscopic techniques for diagnosing GERD based on assessment of esophageal mucosal integrity, particularly MI and mucosal admittance (MA). The authors noted that clinical studies demonstrate that MI typically shows lower distal values with proximal normalization in GERD, while MA tends to be higher in affected areas, with both techniques showing moderate diagnostic accuracy and potential utility in monitoring treatment response. The authors further commented that the MiVu device is complicated and requires training to use, and that the evidence is still limited and heterogeneous, with relatively small studies and variability in diagnostic thresholds across populations and methodologies. Technical challenges include measurement variability due to contact, movement, and intraluminal contents, as well as the need for multiple measurements and operator expertise. Additionally, multicenter data are lacking for broader esophageal conditions, and standardized cutoff values and protocols have not yet been established, limiting widespread clinical adoption.
Marshall-Webb (2024) submitted a narrative review describing MI as an emerging technique for assessing esophageal mucosal integrity and its clinical application in GERD, EoE, and Barrett esophagus. Measures such as mean nocturnal baseline impedance (MNBI) are shown to correlate inversely with acid exposure and may help differentiate GERD from functional disorders, identify individuals more likely to respond to therapy, and provide additional diagnostic support when conventional testing yields equivocal results. The technology can be applied through ambulatory impedance-pH monitoring, high-resolution impedance manometry, or endoscopic probes, offering both functional and real-time assessment of mucosal health. Limitations include the largely observational and narrative nature of the evidence, with variability in measurement techniques, thresholds, and clinical protocols. Many findings are based on small or heterogeneous cohorts, particularly for surgical outcomes and Barrett esophagus, and standardized cutoff values and clinical pathways are not fully established. Availability of specialized equipment is limited, and some methods require technical expertise or are still evolving. Additionally, while MI shows promise as an adjunctive tool, its role relative to established diagnostic modalities and its impact on clinical decision-making require further validation in larger, prospective studies.
Other Information
The ACG clinical guideline (Katz, 2022) provides a comprehensive, evidence-based approach to the diagnosis and management of GERD, emphasizing that diagnosis relies on a combination of symptom assessment, response to empiric proton pump inhibitors (PPIs) therapy, endoscopic findings, and reflux monitoring rather than a single definitive test. Initial management typically involves an empiric trial of PPIs and lifestyle modifications, with escalation to diagnostic testing (endoscopy or pH monitoring) in nonresponders or those with alarm features. The guideline also outlines tailored approaches for refractory symptoms, extraesophageal presentations, and consideration of surgical or endoscopic therapies in selected individuals, while reaffirming PPIs as the mainstay of treatment despite ongoing safety concerns. The guideline also states, “we expect that new diagnostic tools and treatments will be developed and those that we have will be further refined. Mucosal integrity testing, e.g., is available commercially but is not developed sufficiently to warrant discussion in this guideline.”
The ASGE guideline (Desai, 2025) provides an updated, evidence-based framework for the diagnosis and management of GERD, emphasizing a stepwise approach that integrates clinical evaluation, selective use of endoscopy, medical therapy, and endoscopic or surgical interventions. Endoscopy is recommended primarily for individuals with alarm symptoms or risk factors, with careful documentation of objective findings (for example, esophagitis, Barrett esophagus, and gastroesophageal junction anatomy) to guide management. Initial treatment focuses on lifestyle modifications and PPIs, used at the lowest effective dose, while selected individuals with confirmed disease may be considered for endoscopic therapies such as transoral incisionless fundoplication (TIF) or combined approaches depending on anatomy and disease severity. The guideline does not include use of mucosal integrity testing.
| Background/Overview |
Esophageal disorders can be divided into GERD and non-GERD conditions. Gastroesophageal Reflux Disease (GERD) is a chronic condition where contents from the stomach move backward into the esophagus, leading to symptoms like heartburn and regurgitation and, in some cases, damage to the esophageal lining. Non-GERD conditions are esophageal disorders that are not caused by gastroesophageal reflux. An example of a non-GERD condition is eosinophilic esophagitis (EoE), a long-term inflammatory disorder of the esophagus marked by an elevated presence of eosinophils (a type of white blood cell), which can cause symptoms such as trouble swallowing and food impaction. The symptoms of these diseases overlap, sometimes making them difficult to diagnose.
On December 23, 2019, the FDA granted Diversatek, Inc. De Novo classification for the Mucosal Integrity Conductivity (MI) Test System. In 2020 they changed the device name to MiVu Mucosal Integrity Testing System and in 2023 were granted 510(k) clearance by the FDA for the MiVu Esophageal Endo Cap, an accessory to be used with the MiVu Mucosal Integrity Testing System. This device system is used during an endoscopy to measure electrical impedance of the esophageal lining in real-time. According to the Diversatek Healthcare Instructions for use:
The single-use MiVu Esophageal Endo Cap utilizes a small strip of three impedance sensors on a tubular tip that is placed over the working end of an endoscope. This allows for direct control of the placement of the sensors without impeding the optics and working channel of the endoscope.
Using the information from the device like numerical values and/or color-coded patterns, the physician tries to identify disease patterns and determine if the individual has GERD or a non-GERD condition such as EoE.
| Definitions |
Endoscopy: A procedure that uses a flexible tube with a camera (endoscope) to directly view the inside of the digestive tract, often allowing for tissue sampling (biopsy) or treatment during the same procedure.
Eosinophilic Esophagitis (EoE): A chronic inflammatory condition of the esophagus characterized by an increased number of eosinophils (a type of white blood cell), leading to symptoms such as difficulty swallowing and food becoming stuck.
Gastroesophageal Reflux Disease (GERD): A condition in which stomach contents flow back into the esophagus, causing symptoms such as heartburn and regurgitation and, in some cases, mucosal injury.
Mucosal Impedance Testing: A technique that measures the electrical properties of the esophageal lining to assess mucosal integrity, helping to identify conditions like GERD or EoE based on changes in tissue barrier function.
Mucosal Integrity Testing: A broader concept referring to methods used to evaluate how well a mucosal surface (such as the esophagus) functions as a barrier, including techniques like impedance measurement or other assessments of permeability and tissue health.
Non-GERD Disease: Non-GERD conditions refer to esophageal disorders that are not attributable to gastroesophageal reflux. This term is used to distinguish non-reflux-related etiologies from GERD and may include inflammatory, motility, functional, infectious, or medication-induced conditions. Non-GERD is a descriptive classification and not a distinct clinical diagnosis.
| Coding |
The following codes for treatments and procedures applicable to this document are included below for informational purposes. Inclusion or exclusion of a procedure, diagnosis or device code(s) does not constitute or imply member coverage or provider reimbursement policy. Please refer to the member's contract benefits in effect at the time of service to determine coverage or non-coverage of these services as it applies to an individual member.
When services are Investigational and Not Medically Necessary:
For the following procedure codes; or when the code describes a procedure indicated in the Position Statement section as investigational and not medically necessary.
| HCPCS |
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| C9777 |
Esophageal mucosal integrity testing by electrical impedance, transoral, includes esophagoscopy or esophagogastroduodenoscopy |
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| ICD-10 Diagnosis |
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All diagnoses |
| References |
Peer Reviewed Publications:
Government Agency, Medical Society, and Other Authoritative Publications:
| Websites for Additional Information |
| Index |
MiVu Esophageal Endo Cap
MiVu Mucosal Integrity Testing System
Mucosal Integrity Conductivity (MI) Test System
The use of specific product names is illustrative only. It is not intended to be a recommendation of one product over another, and is not intended to represent a complete listing of all products available.
| Document History |
| Status |
Date |
Action |
| New |
05/14/2026 |
Medical Policy & Technology Assessment Committee (MPTAC) review. Initial document development. |
Applicable to Commercial HMO members in California: When a medical policy states a procedure or treatment is investigational, PMGs should not approve or deny the request. Instead, please fax the request to Anthem Blue Cross Grievance and Appeals at fax # 818-234-2767 or 818-234-3824. For questions, call G&A at 1-800-365-0609 and ask to speak with the Investigational Review Nurse.
Federal and State law, as well as contract language, including definitions and specific contract provisions/exclusions, take precedence over Medical Policy and must be considered first in determining eligibility for coverage. The member’s contract benefits in effect on the date that services are rendered must be used. Medical Policy, which addresses medical efficacy, should be considered before utilizing medical opinion in adjudication. Medical technology is constantly evolving, and we reserve the right to review and update Medical Policy periodically.
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