Medical Policies - Surgery

Gastric Electrical Stimulation (GES)


Effective Date:06-15-2018



Gastric electrical stimulation (GES) using the Enterra Therapy System™ may be considered medically necessary for the treatment of chronic, intractable (drug refractory) nausea and vomiting secondary to gastroparesis of diabetic or idiopathic etiology when ALL of the following criteria are met:

Symptomatic gastroparesis ≥ one year, as documented by an initial gastric emptying test; and

Refractory or intolerant to at least two anti-emetic and prokinetic drug classes, and

On stable medical therapy and, if applicable, stable nutritional support during the month prior to initiation of therapy, and

Delayed gastric emptying, defined by > 60% retention at two hours and > 10% retention at four hours, as measured by standardized gastric emptying testing, and

As a humanitarian approved device, the Enterra Therapy System™ may only be used in facilities that have an Institutional Review Board (IRB) to supervise clinical testing of the device.

Gastric electrical stimulation is considered experimental, investigational and/or unproven in all other indications including but not limited to the treatment of obesity.


Gastric electrical stimulation (GES), also referred to as gastric pacing, using an implantable device, has been investigated primarily as a treatment for gastroparesis. Currently available devices consist of a pulse generator, which can be programmed to provide electrical stimulation at different frequencies, connected to intramuscular stomach leads that are implanted during laparoscopy or open laparotomy (see Regulatory Status section).

Gastroparesis is a chronic disorder of gastric motility characterized by delayed emptying of a solid meal. Symptoms include bloating, distension, nausea, and vomiting. When severe and chronic, gastroparesis can be associated with dehydration, poor nutritional status, and poor glycemic control in diabetic patients. While most commonly associated with diabetes, gastroparesis is also found in chronic pseudo-obstruction, connective tissue disorders, Parkinson disease, and psychological pathologic conditions. Some cases may not be associated with an identifiable cause and are referred to as idiopathic gastroparesis. Treatment of gastroparesis includes prokinetic agents, such as metoclopramide, and antiemetic agents, such as metoclopramide, granisetron, or ondansetron. Severe cases may require enteral or total parenteral nutrition.

GES has also been investigated as a treatment of obesity as a technique to increase a feeling of satiety with subsequent reduced food intake and weight loss. The exact mechanisms resulting in changes in eating behavior are uncertain but may be related to neuro-hormonal modulation and/or stomach muscle stimulation.

There are no GES devices approved by the U.S. Food and Drug Administration for the treatment of obesity. The Transcend® Implantable Gastric Stimulation device, acquired by Medtronic in 2005, is available in Europe for treatment of obesity.

Regulatory Status

In 2000, the Gastric Electrical Stimulator (GES) system (now called Enterra™ Therapy System; Medtronic, Minneapolis, MN) was approved by the U.S. Food and Drug Administration (FDA) through the humanitarian device exemption process ((HDE Approval H990014). The GES system consists of 4 components: the implanted pulse generator, 2 unipolar intramuscular stomach leads, the stimulator programmer, and the memory cartridge. With the exception of the intramuscular leads, all other components have been used in other implantable neurologic stimulators, such as spinal cord or sacral nerve stimulation. The intramuscular stomach leads are implanted either laparoscopically or during a laparotomy and are connected to the pulse generator, which is implanted in a subcutaneous pocket. The programmer sets the stimulation parameters, which are typically set at an “on” time of 0.1 second alternating with an “off” time of 5.0 second.


This medical policy was originally created in December 2002 and was regularly updated with searches of the MEDLINE database. The most recent literature review was performed through April 2017. The following is a summary of the key findings to date.

Gastric Electrical Stimulation for Gastroparesis

Systematic Reviews

Several systematic reviews of studies on Gastric Electrical Stimulation (GES) for gastroparesis have been published, (1, 2, 3) the most recent and comprehensive of which was a systematic review and meta-analysis published by Levinthal et al. (2017). (1) To be included in the review, studies needed to include adults with established gastroparesis, report patient symptom scores and administer treatment for at least 1 week. A total of 5 randomized controlled trials (RCTs) and 13 non-RCTs meeting criteria were identified. Pooled analysis of data from the 5 RCTs (n=185 patients) did not find a statistically significant difference in symptom severity when the GES was turned on versus off (standardized mean difference [SMD], 0.17; 95% confidence interval [CI], -0.06 to 0.40; p=0.15). In addition, another pooled analysis did not find a statistically significant difference in nausea severity scores when the GES was on or off (SMD = -0.143; 95% CI, -0.50 to 0.22; p=0.45). In pooled analysis of 13 open-label single-arm studies and data from open-label extensions of 3 RCTs, the mean total symptom severity score decreased 2.68 (95% CI, 2.04 to 3.32) at follow-up compared with a mean baseline score of 6.85 (95% CI, 6.28 to 7.42). The rate of adverse events in the immediate postoperative period (reported in 7 studies) was 8.7% (95% CI, 4.3% to 17.1%). The in-hospital mortality rate within 30 days of surgery was 1.4% (95% CI, 0.8% to 2.5%), the rate of reoperations (up to 10 years of follow-up) was 11.1% (95% CI, 8.7% to 14.1%), and the rate of device removal was 8.4% (95% CI, 5.7% to 12.2%).

Randomized Controlled Trials

Representative crossover RCTs are described next. In 2003, Abell et al. reported findings of the Worldwide Anti-Vomiting Electrical Stimulation Study (WAVESS). (4) This double-blind crossover study, initially described in FDA materials, included 33 patients with intractable idiopathic or diabetic gastroparesis. (5) The primary end point was a reduction in vomiting frequency, as measured by patient diaries. In the initial phase of the study, all patients underwent implantation of the stimulator and were randomly and blindly assigned to stimulation on or stimulation off for the first month, with crossover to off and on during the second month. Baseline vomiting frequency was 47 episodes per month, which declined in both on and off groups to 23 to 29 episodes, respectively. However, no statistically significant differences were found in the number of vomiting episodes between the 2 groups, suggesting a placebo effect. In the second, open-label, phase of the trial, all patients had their stimulators turned on for the remainder of the 6- to 12-month follow-up. During this period, vomiting frequency declined in both the idiopathic and diabetic subgroups.

In 2010, McCallum et al. reported on a crossover RCT evaluating GES (Enterra therapy) in patients with chronic intractable nausea and vomiting from diabetic gastroparesis (DGP). (6) In this study, 55 patients with refractory DGP (5.9 years of DGP) were given implants of the Enterra system. After surgery, all patients had the stimulator turned on for 6 weeks and then were randomly assigned to groups that had consecutive 3-month crossover periods with the device on or off. After this period, the device was turned on in all patients, and they were followed up unblinded for 4.5 months. During the initial 6-week phase with the stimulator turned on, the median reduction in weekly vomiting frequency (WVF) compared with baseline was 57%. There was no significant difference in WVF between patients who had the device turned on or off during the 3-month crossover period. At 1 year, the WVF of all patients was significantly lower than baseline values (median reduction, 68%; p<0.001). One of the patients had the device removed due to infection; 2 patients required surgical intervention due to lead-related problems.

In 2013, McCallum et al, evaluated GES (Enterra system) in patients with chronic vomiting due to idiopathic gastroparesis in a randomized, double-blind crossover trial.(7) In this study, 32 patients with nausea and vomiting associated with idiopathic gastroparesis, which was unresponsive or intolerant to prokinetic and antiemetic drugs, received Enterra implants and had the device turned on for 6 weeks. Subsequently, 27 of these patients were randomized to have the device turned on or off for 2 consecutive 3-month periods. Twenty-five of these subjects completed the randomized phase; of note, 2 subjects had the device turned on early, 2 subjects had randomization assignment errors, and 1 subject had missing diaries. During the initial 6-week on period, all subjects demonstrated improvements in their WVF, demonstrating a median reduction of 61.2% compared with baseline (17.3 episodes/week at baseline vs 5.5 episodes/week at 6 week postimplant, p<0.001). During the on-off crossover phase, subjects demonstrated no significant differences between the on and off phase in the study’s primary end point, median WVF (median, 6.4 in on-phase vs 9.8 in off-phase; p=1.0). Among the 19 subjects who completed 12 months of follow-up, there was an 87.1% reduction in median WVF compared with baseline (17.3 episodes/week at baseline vs 2 episodes/week at 12-month follow-up, p<0.001). Two subjects required surgical intervention for lead migration/dislodgement or neurostimulator migration.

Section Summary: Gastric Electrical Stimulation for Gastroparesis

Five crossover RCTs have been published. A 2017 meta-analysis of these 5 RCTs did not find a significant benefit of GES on the severity of symptoms associated with gastroparesis. Patients generally reported improved symptoms at follow-up whether or not the device was turned on suggesting a placebo effect. For example, there was not a significant difference in the on versus off position in symptom severity or nausea severity scores.

GES for Obesity

There has only been 1 RCT published on GES for the treatment of obesity: the SHAPE trial. In 2009, Shikora et al. reported on a randomized controlled, double-blind study to evaluate GES for the treatment of obesity. (8) All 190 patients participating in the study received an implantable gastric stimulator and were randomized to have the stimulator turned on or off. All patients were evaluated monthly, participated in support groups, and reduced their diet by 500 kcal/d. At 12-month follow-up, there was no statistically significant difference in excess weight loss between the treatment group (weight loss, 11.8%±17.6%) and the control group (weight loss, 11.7%±16.9%) using intention-to-treat analysis (p=0.717).

Small case series and uncontrolled prospective trials have reported positive outcomes in weight loss and maintenance of weight loss along with minimal complications. (9-14) However, interpretation of these uncontrolled studies is limited.

Summary of Evidence

For individuals who have gastroparesis who receive GES, the evidence includes randomized controlled trials (RCTs) and systematic reviews. Relevant outcomes are symptoms and treatment-related morbidity. Five crossover RCTs have been published. A 2017 meta-analysis of these 5 RCTs did not find a significant benefit of GES on the severity of symptoms associated with gastroparesis. Patients generally reported improved symptoms at follow-up whether or not the device was turned on, suggesting a placebo effect.

For individuals who have obesity who receive GES, the evidence includes 1 published randomized study. Relevant outcomes are change in disease status and treatment-related morbidity. The published RCT (the SHAPE trial) did not show significant improvement in weight loss with GES compared with sham stimulation. The evidence is insufficient to determine the effects of the technology on health outcomes.

Practice Guidelines and Position Statements

National Institute for Health and Care Excellence

In 2014, the National Institute for Health and Care Excellence issued guidance on gastroelectrical stimulation for gastroparesis that made the following recommendations (15):

1.1 “Current evidence on the efficacy and safety of gastric electrical stimulation for gastroparesis is adequate to support the use of this procedure with normal arrangements for clinical governance, consent, and audit.

1.2 During the consent process, clinicians should inform patients considering gastric electrical stimulation for gastroparesis that some patients do not get any benefit from it. They should also give patients detailed written information about the risk of complications, which can be serious, including the need to remove the device.

1.3 Patient selection and follow-up should be done in specialist gastroenterology units with expertise in gastrointestinal motility disorders, and the procedure should only be performed by surgeons working in these units.

1.4 Further publications providing data about the effects of the procedure on symptoms in the long term and on device durability would be useful.”

American College of Gastroenterology

The American College of Gastroenterology published a clinical practice guideline on management of gastroparesis in 2013. (16) The recommendation was that “GES [gastric electrical stimulation] may be considered for compassionate treatment in patients with refractory symptoms, particularly nausea and vomiting. Symptom severity and gastric emptying have been shown to improve in patients with DG [diabetic gastroparesis], but not in patients with IG [idiopathic gastroparesis] or PSG [postsurgical gastroparesis]. [Conditional recommendation (there is uncertainty about trade-offs), moderate level of evidence (further research would be likely to have an impact on the confidence in the estimate of effect).]”


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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.


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

CPT Codes

43647, 43648, 43881, 43882, 64590, 64595, 95980, 95981, 95982


C1767, E0765

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 <>.


1. Levinthal DJ, Bielefeldt K. Systematic review and meta-analysis: Gastric electrical stimulation for gastroparesis. Auton Neurosci. Jan 2017; 202:45-55. PMID 27085627

2. Chu H, Lin Z, Zhong L, et al. Treatment of high-frequency gastric electrical stimulation for gastroparesis. J Gastroenterol Hepatol. Jun 2012; 27(6):1017-1026. PMID 22128901

3. Lal N, Livemore S, Dunne D, et al. Gastric Electrical Stimulation with the Enterra System: A Systematic Review. Gastroenterol Res Pract. 2015; 2015:762972. PMID 26246804

4. Abell T, McCallum R, Hocking M, et al. Gastric electrical stimulation for medically refractory gastroparesis. Gastroenterology. Aug 2003; 125(2):421-428. PMID 12891544

5. U.S. Food and Drug Administration. FDA Summary of Safety and Probable Benefit. 2010; <>. (accessed January, 2017).

6. McCallum RW, Snape W, Brody F, et al. Gastric electrical stimulation with Enterra therapy improves symptoms from diabetic gastroparesis in a prospective study. Clin Gastroenterol Hepatol. Nov 2010; 8(11):947-954; quiz e116. PMID 20538073

7. McCallum RW, Sarosiek I, Parkman HP, et al. Gastric electrical stimulation with Enterra therapy improves symptoms of idiopathic gastroparesis. Neurogastroenterol Motil. Oct 2013; 25(10):815-e636. PMID 23895180

8. Shikora SA, Bergenstal R, Bessler M, et al. Implantable gastric stimulation for the treatment of clinically severe obesity: results of the SHAPE trial. Surg Obes Relat Dis. Jan-Feb 2009; 5(1):31-37. PMID 19071066

9. Cigaina V. Gastric pacing as therapy for morbid obesity: preliminary results. Obes Surg. Apr 2002; 12 Suppl 1:12S-16S. PMID 11969102

10. Cigaina V, Hirschberg AL. Gastric pacing for morbid obesity: plasma levels of gastrointestinal peptides and leptin. Obes Res. Dec 2003; 11(12):1456-1462. PMID 14694209

11. D'Argent J. Gastric electrical stimulation as therapy of morbid obesity: preliminary results from the French study. Obes Surg. Apr 2002; 12 Suppl 1:21S-25S. PMID 11969104

12. De Luca M, Segato G, Busetto L, et al. Progress in implantable gastric stimulation: summary of results of the European multi-center study. Obes Surg. Sep 2004; 14 Suppl 1:S33-39. PMID 15479588

13. Favretti F, De Luca M, Segato G, et al. Treatment of morbid obesity with the Transcend Implantable Gastric Stimulator (IGS): a prospective survey. Obes Surg. May 2004; 14(5):666-670. PMID 15186636

14. Shikora SA. Implantable gastric stimulation for the treatment of severe obesity. Obes Surg. Apr 2004; 14(4):545-548. PMID 15130236

15. National Institute of Health and Care Excellence. Gastroelectrical stimulation for gastroparesis [IPG489]. 2014; <>. (accessed January 23, 2017).

16. Camilleri M, Parkman HP, Shafi MA, et al. Clinical guideline: management of gastroparesis. Am J Gastroenterol. Jan 2013; 108(1):18-37; quiz 38. PMID 23147521

17. Gastric Electrical Stimulation. Chicago, Illinois: Blue Cross Blue Shield Association Medical Policy Reference Manual (2017 February) Surgery 7.01.73.

Policy History:

Date Reason
6/15/2018 Reviewed. No changes.
7/15/2017 Document updated with literature review. Coverage unchanged.
3/15/2016 Reviewed. No changes.
3/15/2015 Document updated with literature review. Coverage unchanged.
6/1/2011 CPT/HCPCS code(s) updated
12/15/2010 Document updated with literature review. Coverage unchanged.
7/1/2008 Revised/updated entire document
7/1/2006 Revised/updated entire document
10/1/2003 CPT/HCPCS code(s) updated
8/1/2002 New medical document

Archived Document(s):

Title:Effective Date:End Date:
Gastric Electrical Stimulation (GES)06-15-201804-30-2019
Gastric Electrical Stimulation (GES)07-15-201706-14-2018
Gastric Electrical Stimulation (GES)03-15-201607-14-2017
Gastric Electrical Stimulation (GES)03-15-201503-14-2016
Gastric Electrical Stimulation (GES)06-01-201103-14-2015
Gastric Electrical Stimulation (GES)12-15-201005-31-2011
Gastric Electrical Stimulation07-01-200812-14-2010
Gastric Electrical Stimulation07-01-200606-30-2008
Gastric Electrical Stimulation08-01-200206-30-2006
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