Effects of Obesity Surgery on GERD and Esophageal Motility

Introduction

Obesity, defined as a body mass index (BMI) >30 kg/m², currently affects 40% of adults and accounts for 21% of annual health expenditure in the United States. ¹ Treatment options for obesity include lifestyle modification, drug therapy, and bariatric surgery. While all patients should be counseled on dietary/exercise modifications, lifestyle interventions have not shown to result in sustained weight loss over time, and use of pharmacologic therapy has been limited by side effects. Bariatric surgery is a treatment option for patients with a BMI > 40 kg/m², or for those with a BMI > 35 kg/m²and an obesity related co-morbidity. Unlike lifestyle interventions and pharmacologic therapy for obesity, bariatric surgery has been increasingly popular as it has demonstrated significant improvement in obesity related comorbidities and all-cause mortality. ²

Obesity has been associated with gastrointestinal conditions such as gastroesophageal reflux disease (GERD) and esophageal dysmotility. GERD is considered an obesity related comorbidity with obese patients being 2.5 times more likely to have GERD compared to non-obese patients. ³ This is due to multiple factors such as impaired lower esophageal sphincter function, increased gastroesophageal pressure gradient secondary to abdominal adipose tissue and higher incidence of hiatal hernia development. Esophageal dysmotility in the general population has been estimated at 5%, but studies have shown 35% to 61% of obese patients have esophageal manometric abnormalities on manometry performed prior to bariatric surgery.^4,5 The prevalence of GERD and esophageal dysmotility among obese patients becomes important as bariatric surgery can lead to changes in esophageal motility and the development or worsening of GERD symptoms. This review explores the effects of the various types of bariatric surgery on GERD and esophageal motility with focus primarily on sleeve gastrectomy and Roux-en-Y gastric bypass as well as laparoscopic adjustable gastric banding given the significant changes in esophageal function seen after this surgery.

Sleeve Gastrectomy

Sleeve gastrectomy (SG) currently compromises more than half of bariatric surgeries performed. ⁶ Reduction in stomach size after SG can lead to improvement in GERD due to a decrease in the gastroesophageal pressure gradient secondary to weight loss, decreased acid reflux production and increased gastric emptying. However, multiple other factors can contribute to worsening GERD after SG. The lower esophageal sphincter (LES) can be weakened due to dissection of the angle of His and disruption of the sling fibers that contribute to LES competency. The tubular sleeve anatomy can also lead to increased intragastric pressure and decreased gastric compliance secondary to removal of the fundus. There is a higher risk of hiatal hernia after SG, and anatomic abnormalities of the sleeve (ie, narrowing or twisting of the sleeve, dilation of the proximal stomach or retention of the fundus) can lead to increased reflux. Thus, multiple factors play a role in determining whether patients have GERD after SG.

Results of early studies regarding the prevalence of GERD after SG were variable secondary to subjective symptom and medication use reporting as well as various follow up intervals. However, a systematic review of more than 10, 000 patients from 46 studies noted worsening of GERD symptoms in 19% of patients and de-novo GERD symptoms in 23% after SG. ⁷ In contrast to subjective factors such as medication use and symptom reporting, there have been several studies that have performed 24 hour pH impedance testing to objectively measure pathologic acid reflux before and after SG. The majority of studies found an increase in total % acid exposure time (AET) after surgery.^8-13 A few studies looked specifically at the development of de novo GERD after SG. Two studies found 36% to 69% of patients had developed de-novo GERD after SG at mean follow up of 6 to 12 months.^10,13 Of note, Rebecchi et al ¹² found a much lower de-novo GERD rate of 5.4% at 24 month follow up. Among patients with pre-existing reflux before SG, there was no statistically significant difference in 24 hour pH testing parameters after SG based on 3 studies.^9,11,14 In summary, there is a trend toward increased total %AET and development of de novo GERD after SG.

Endoscopic evidence of GERD such as erosive esophagitis (EE) has also been evaluated after SG. In a study of 66 patients, Tai et al ¹⁵ found a significant increase in EE (16.7% vs 66.7%) at 1 year after SG with 64% of patients developing de-novo EE with EE frequently found in the presence of a hiatal hernia. Another study of 147 patients also found increased rates of EE (8.2%-30% postop) with 25% developing de-novo EE. ¹⁶ The increased incidence of EE after SG has also been noted in rats who underwent sleeve gastrectomy and was independent of amount of weight lost. ¹⁷ Based on these findings, EE is considered a relative contraindication to SG. ¹⁸

There has also been studies looking at another endoscopic marker of GERD, Barrett’s esophagus (BE). While an initial study reported BE in 1.2% of SG patients, subsequent studies have noted higher rates of de-novo BE.^19-23 Of note, all reported cases of de-novo BE were <3 cm with no evidence of dysplasia. Qumseya et al ²⁴ recently performed a meta-analysis of 10 studies consisting of 680 SG patients and found a pooled prevalence rate of de novo BE to be 11.6% with most cases occurring 3 years after SG. There was no difference in the likelihood of having BE based on the presence of symptoms. Currently, most bariatric surgeons surveyed would not perform SG in the setting of known BE. ²⁵ At this time, there is no guidelines on screening for BE after SG, but while acknowledging that further studies are needed, the American Society for Metabolic and Bariatric Surgery (ASMBS) currently recommends that clinicians consider screening for BE with endoscopy at 3 or more years after SG irrespective of GERD symptoms. ²⁶

Based on the literature showing increased GERD symptoms and development of de-novo GERD, EE and BE after SG, SG is not recommended as the bariatric surgery of choice for patients with GERD. Given that 30.4% of SG patients undergo conversion to RYGB due to GERD based on a recent systematic review, thorough evaluation for GERD symptoms should be performed before surgery to avoid the need for revisional surgery. ²⁷ Pre-operative evaluation for GERD with objective pH testing should be strongly considered as symptoms alone have not been a reliable indicator of GERD, and a positive preoperative pH test in asymptomatic patients has been found to be a predictive factor for the development of GERD symptoms after SG. ²⁸ In patients with GERD who do not wish to undergo RYGB as a primary bariatric surgery, there have been some reports of performing SG combined with fundoplication, and a recent survey of bariatric surgeons reported that 77% would consider performing SG with fundoplication in obese patients with GERD. ²⁵ However, a systematic review and meta-analysis of 485 patients who underwent concomitant SG and fundoplication showed subjective improvement in GERD symptoms at a mean follow up of 1 to 3 years, but high postoperative gastric perforation and overall complication rates compared to only undergoing SG. ²⁹ Another consideration for GERD treatment in SG patients is magnetic lower esophageal sphincter augmentation (MSA) via placement of a LINX device, a band of magnetic titanium rings, around the LES. Data available on LINX placement after SG have reported improvement in subjective outcomes such as GERD symptoms and PPI use. ³⁰ While a database study found MSA placement at the time of SG to have no difference in morbidity or mortality at 30 day follow up, longer follow up studies are needed to determine efficacy and safety. ³¹

As most studies have focused on GERD outcomes, understanding the effects of SG on esophageal motility has been limited as studies have focused primarily on manometric factors that influence development of GERD such as LES pressure. Results have been variable with some finding increased LES resting pressure,^32,33 others reporting decreased LES resting pressure^8,11,34,35 and other studies reporting no change to LES resting pressure after SG.^12,36 In regard to the esophageal body motility, there was a trend toward development of esophageal body hypocontractility after SG. Del Genio et al ³⁶ noted that there was an increase in percentage of ineffective swallows from 10% to 46%, and Burgerhart et al ⁸ noted a decrease in the mean distal contractile integral. Gorodner et al ¹¹ noted an increase in IEM diagnoses from 0% to 7% after SG, and Mion et al noted that 37% of patients had IEM after SG though no preoperative manometries were available to assess what changes occurred after surgery. ³⁷ In contrast to the above studies, one study found an increase in % of normal swallows. ³⁵ In a recent retrospective study looking at the effects of SG with pre-existing esophageal motility disorders, Sans et al noted patients had the same diagnoses on repeat HRM after SG as the preoperative HRM though it was unclear when postoperative HRM was completed. One third of the patients (among which 25% had achalasia and 50% had a hypercontractility disorder) required conversion to RYGB due to dysphagia and reflux symptoms with resolution of symptoms after conversion. Based on these findings, the authors felt that RYGB should be considered instead of SG in patients with esophageal motility disorders especially achalasia and hypercontractile esophagus. ³⁸ Further large prospective studies using high resolution esophageal manometry and the current classification system for esophageal motility disorders are needed to determine the changes in esophageal motility that occur after SG.

Roux-en-Y-Gastric Bypass

Weight loss is achieved after RYGB through restricting the size of the stomach via creation of a small gastric pouch and through malabsorption as a portion of the small bowel is bypassed. RYGB is currently considered the bariatric surgery of choice by surgical and GI societies for obese patients with GERD.^39,40 Improvement in reflux after RYGB is due to several mechanisms. The gastric pouch contains few acid producing parietal cells and also leads to increased gastric emptying. Due to diversion of the duodenal limb, there is also decreased bile acid reflux. Studies show that RYGB leads to improvement in GERD symptoms and reduction in anti-reflux medication use postoperatively and a decrease in pathologic levels of reflux on pH testing. In large database studies, RYGB has been shown to have lower rates of postoperative GERD symptoms and EE compared to LAGB and SG. ⁴¹ Several large studies have compared GERD symptoms between patients undergoing SG and RYGB. A study of 38, 000 patients from the Bariatric Outcomes Longitudinal Database found higher rates of GERD symptom remission among RYGB compared to SG patients (62.8% vs 15.9%), ⁴² and similar results were found in two large prospective randomized control trials of bariatric patients at 5 year follow up.^43,44

Studies have evaluated whether obese patients would have similar outcomes undergoing an anti-reflux surgery such as fundoplication rather than RYGB, and results have shown increased operating times and frequent GERD recurrence among obese patients compared to normal weight patients undergoing fundoplication. In a prospective study following patients over a mean of 16 years after fundoplication, obese patients were significantly more likely to have reflux (defined as a positive pH study and/or EE on endoscopy) compared to normal weight patients (27.5% vs 2.3%, P < .001). ⁴⁵ Given the high likelihood of reflux recurrence and complication rate after failed fundoplication, RYGB is preferred for treatment of GERD in obese patients as it leads to better reflux outcomes and improvement in obesity related comorbidities.

While there are limited studies in this area, RYGB has not been shown to negatively impact esophageal motility, and it is currently recommended for obese patients found to have esophageal dysmotility. While some studies found a decrease in LES pressure and others have reported no change in LES pressure, a systematic review of 11 studies consisting of 469 patients found that overall LES pressure did not change after RYGB on esophageal manometry. ⁴⁶ A few studies have noted in increased incidence of ineffective esophageal motility after RYGB, but the clinical significance of this is unclear.^47,48 Though there is not strong data on the effects of RYGB on esophageal motility, it appears to affect esophageal motility the least compared to other types of bariatric surgery.

Laparoscopic Adjustable Gastric Banding

Laparoscopic adjustable gastric banding (LAGB) has fallen out of favor as a bariatric surgery due to its effects on the esophagus, failure to maintain sustained weight loss and other long term complications. In a systematic review of more than 3, 000 patients who had LAGB surgery, patients initially reported improvement in reflux symptoms and medication use. ⁴⁹ In conjunction with these subjective findings, there was also improvement in total %AET and DeMeester scores at short term follow up of 6 weeks which is likely secondary to LES augmentation from the band. However, GERD was found to worsen or develop at long term follow up of 2 to 5 years. One in 5 LAGB patients were noted to have new onset EE on endoscopy, and 15% noted worsening or de novo GERD. The increase in GERD may be related to slippage of the band, pouch dilation or development of esophageal dysmotility leading to poor acid clearance.

While LAGB adversely affects GERD symptoms, LAGB has been primarily abandoned as a bariatric surgery option because of esophageal motility complications that develop over time. At a follow up time of 8 years, a study of 167 LAGB patients found that 68% had developed esophageal dysmotility. ⁵⁰ Findings on postoperative esophageal manometry show impaired LES relaxation with ineffective esophageal motility or absent contractility of the esophageal body. ⁵¹ These patients have also been noted to have increased intrabolus pressure on esophageal manometry which correlates with the presence of symptoms. ⁵² Anatomic changes such as esophageal dilation has also been found to occur in greater than >50% of patients with LAGB. ⁵³ Pseudoachalasia from LAGB, a condition where there is severe dilation and aperistalsis of the esophagus, has been found in 2% of LAGB patients and appears to develop after a mean postoperative interval of 3 years. ⁵⁴ While many LAGB patients have significant esophageal dysmotility and dilation after surgery, no correlation has been found between the presence of esophageal dysmotility and patient symptoms. However, there is some degree of reversibility in esophageal dysmotility and symptom improvement with band removal. One study even noted that 87% had improvement in esophageal dilation after band removal. ⁵⁰ Given that symptoms do not correlate with esophageal dysmotility findings in LAGB patients and there is potential for reversibility of esophageal dysfunction with band removal, clinicians should consider pursuing esophageal workup and discuss band removal with LAGB patients.

Conclusion

The effect of bariatric surgery on the esophagus varies depending on the type of surgery. RYGB is the bariatric surgery of choice for GERD though novel methods to address GERD among SG patients are being explored. Development of GERD among SG patients can be variable as it is dependent on multiple factors. While more research is needed on esophageal motility after bariatric surgery, RYGB appears to have the least effect on esophageal motility. In contrast, LAGB has fallen out of favor as a bariatric surgery option secondary to significant adverse effects on esophageal motility and GERD. Clinicians should consider counseling patients on band removal to prevent esophageal dysmotility and dilation. While there are no guidelines requiring esophageal manometry and/or pH testing before bariatric surgery, studies have shown that preoperative esophageal manometry and pH testing can change surgical planning.^55,56 As many obese patients have GERD and possibly esophageal dysmotility, there should be a low threshold to perform a thorough objective evaluation of esophageal motility and acid reflux before bariatric surgery to optimize surgical outcomes.