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IFSO Consensus Conference on OAGB-MGB

IFSO International Consensus Conference on OAGB-MGB (part 4)

The IFSO International Consensus Conference on One Anastomosis Gastric Bypass (OAGB-MGB), sponsored by Ethicon, took place on July 18-19 2019, at the Johnson and Johnson Institute, in Hamburg, Germany.

The IFSO International Consensus Conference on One Anastomosis Gastric Bypass (OAGB-MGB), sponsored by Ethicon, took place on July 18-19 2019, at the Johnson and Johnson Institute, in Hamburg, Germany. At the conference, the Expert Panel reviewed and discussed both the published findings for the procedures and the participants’ own data and subsequently voted to see whether there was consensus or no consensus on the specific topics.

A consensus statement discussing the findings will be submitted to a journal in the next few months. The topics under discussion at the conference were: 1) Fundamentals of OAGB-MGB 2) Indications and Selection of Patients 3) Technical Systematization 4) Complications/Controversies: Diagnosis, Treatment and Prevention 5) Revision, Use as Revisional Surgery and Follow Up. Below are summaries of fourth session - Complications/Controversies: Diagnosis, Treatment and Prevention.

Module IV: Complications/Controversies: Diagnosis, Treatment and Prevention

A Comparison between OAGB and RYGB

Dr Michel Suter (Switzerland) stated that OAGB is now the third most commonly performed procedure, after sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB). Several case series have demonstrated that OAGB is comparable to RYGB in terms of early postoperative complications and overall risks, and several series have also demonstrated that OAGB is effective regarding weight loss and resolution or improvement of comorbidities, notably of metabolic nature.

Michel Suter

Citing the literature, Dr Suter revealed there are three randomised controlled trials comparing OAGB with RYGB:

  • Lee et al published a small RCT in 2005 comparing RYGB and OAGB in a total of 80 patients, with two-year results and showed a reduced operative and a non-significant trend towards fewer complications with OAGB, no difference in weight results after two years, and more anaemia after OAGB.
  • Ruiz-Tovar et al published in 2019 a larger RCT comparing OAGB, RYGB and SG in a total of 600 patients. They showed no difference in operative morbidity between the procedures, but better weight loss and better control of comorbidities, notably diabetes, dyslipidaemia and hypertension, after OAGB. However, the study protocol was not published in an official body, and the manuscript fails to mention IRB approval.  Furthermore, OAGB in this study was done with a longer than usual biliopancreatic limb and a shorter than usual common limb, representing an increased risk for nutritional deficiencies and proteocaloric malnutrition.
  • Robert et al published this year the results of the YOMEGA study, comparing 117 OAGB with 117 RYGB and showed a shorter operative duration for OAGB and similar early complication rates. Weight loss after two years was not significantly different between the two groups. In patients with type two diabetes, remission rates were similar between the 2 techniques, but there were more complete remissions after OAGB (60 vs 38 %). There were more overall and surgery-related serious adverse events in the OAGB group, with 9 severe nutritional complications in the latter compared to none in the RYGB group.

“The current published literature shows that OAGB takes less time to do, provides slightly better weight loss and has slightly more effects on metabolic comorbidities than RYGB, at the expense of more nutritional complications, more anaemia, and with a risk related to bile reflux that needs further evaluation,” he concluded.

How to deal with unexpected intraoperative findings?

Professor Osama Taha (Egypt) began by stating that advances in peri-operative imaging and diagnostic studies have enabled surgeons to have access to important surgical diagnoses before entering the operating theatre, and have helped to reduce the morbidity, mortality and complication rates.

Osama Taha

He showed that outcomes of OAGB from the largest published series showed low rates of long-term complications that required surgical repair.  However, undiagnosed or unexpected intraoperative findings and complications from surgery can still arise and cause challenges in decision making and treatment. However, guidance on how to treat these intraoperative occurrences is difficult to find.

He advised that in instances of internal bleeding, he uses the SNoW absorbable haemostat (a cellulose derivative) that prevents the oozing that may happen through the staple line to stop the bleeding. For acute marginal ulcers, he uses sutures then a stapler, and the ulcer can be made more secure by creating an omental flap. When presented with a gastric pouch leak, the leak should be sutured (followed by omental flap).

He concluded his presentation by stating that more standardisation needed on pouch creation during MGB as too much variation is leading more complications.

Leaks and Bleeding

Dr Francisco Pacheco (Chile) stated that bleeding represents one of the most frequent immediate postoperative complications of all kind of techniques in bariatric surgery. The cause can be bleeding from the staple line into the digestive tube or into peritoneal cavity, also the omentum can bleed or subsequent bleeding from marginal ulcers. Bleeding can generally be controlled conservatively, usually managed with transfusion therapy only occasionally requiring endoscopic procedures or surgery.

Francisco Pacheco

Carbajo et al. reported an incidence of major complications of 2.7%, bleeding represented 0.9%. Chetan et. Cols, published a systematic review of 12,807 patients who underwent OAGB, and reported a major bleeding was defined as requiring transfusion, reintervention or endoscopic procedures and accounted for 1.12%.

In Dr Pacheco’s own experience in approximately 900 RYGB the most frequently site of bleeding was the staple line of jejunum jejunum anastomosis, only two patients required transfusion, and none required reintervention.

The rate of anastomosis leakage described by Carbajo et al. was 1%, compared with Rudledge who reported an incidence of 1.1% and Chevallier et al. who reported a 0.6% leakage rate.

Chetan et. Cols reviewed 12,807 patients and found the rate of leakage to be 0.96% and Ruiz-Tovar described an incidence of leakage of 2, 1.5 and 0% in relation to sleeve gastrectomy, RYGB and OAGB, respectively.

“When comparing OAGB and RYGB, major bleeding and leakage rates are similar,” he concluded.

Gastric ulcer

Dr Gurvinder Singh Jammu (India) said that the incidence of marginal ulceration in MGB- OAGB is not statistically different from RYGB, with a reported incidence rate of 0.5 to 5%, with smoking and NSAIDS considered to be the main culprits, although a high acid production, alcohol, steroids, prolonged use of anti-coagulants and H.pylori can also cause marginal ulcer.

Gurvinder Singh Jammu

Upper GI endoscopy is the procedure of choice to diagnose and biopsies should be taken from different parts of the stomach to evaluate H.pylori infection, rule out gastro gastric fistula, look for the signs of erythema at the margins of anastomosis, look for perforation. The management of marginal ulcer is based on its etiological factor

Complicated, non-healing, obstructing, bleeding, penetrated and perforated marginal ulcers require surgical intervention, and surgical management can comprise of:

  • Over sewing of perforation with a jejunal and omental patch
  • Primary closure with absorbable suture and placement of close suction drain
  • Complete reconstruction of the gastrojejunostomy
  • For bile diversion sometimes one may have to do Braun's reconstruction or Roux-en-Y reconstruction

Dr Jammu added that it was important to pay attention to technical aspects of surgery such as avoiding anastomotic ischaemia, performing gastrojejunostomy without tissue tension ensuring appropriate blood supply to stomach and jejunum. Early diagnosis by symptomatology and upper GI endoscopy will ensure timely management with high cure rates.

The role of the bile: the good and the bad

Evaluating the role of bile, Rudolf Weiner (Germany) said that the entero-hepatic circulation (EHC) of bile acids (BA) and its role in digestion (assimilation) and intestinal uptake (absorption) of nutrients is well-known and new findings have shown the metabolic effects and a strong interaction with the microbiome.

Rudolf Weiner

He explained that after all types of gastric bypass procedures and biliopancreatic diversions the circulation of bile acids are changed. Bile reabsorption in the biliopancreatic limb with a consecutive mild malabsorption is a basic principle of the MGB/OAGB procedure, although the role of bile in the development of gastric cancer seems to be overestimated.

The gastric bypass with a longer biliopancreatic limb (MGB/OAGB) can introduce a proximal bile acid reabsorption before the process of assimilation starts. The common channel is lacking on bile as the bile acids have been reabsorbed before. Therefore, this type of surgery is bile-saving and in the long-term the pool of bile acid will not be reduced.

The chologenic diarrhoea is one of the bad side effects of bile acid, but does not exist after MGB/OAGB, if the BL is limited in the length. This is a clear benefit of MGB/OAGB in respect of QoL and long-term preservation of the bile acid pool.

Bile is not cancerogenic in general, but can be one co-factor in the development of cancers. However, considerable indirect evidence, obtained more recently, supports the view that bile acids are carcinogens in humans.

He explained that after gastric bypass surgery the majority of reported cancer cases have been located in the larger remnant stomach, compared with MGB/OAGB that has a smaller channel to a significant smaller remnant stomach.

“The first case of anastomotic cancer after MGB/OAGB is not the signal to stop this type of bariatric surgery. We had to establish evidence-based recommendations for postoperative endoscopic controls – after sleeve gastrectomy and after gastric bypass surgery. What we must decide is the role of upper GI endoscopy!”

The Risk of Carcinogenesis

Mr Peter Small (UK) said that the uptake of MGB/OAGB has been sporadic across the world with some clinicians expressing concerns regarding the risk of gastric or oesophageal cancer as a consequence of chronic alkaline reflux of bile. Conversely, it is well known that bariatric surgery, by inducing weight loss and metabolic changes, reduces cancer risk.

He said that joining a loop of jejunum to a gastric tube will result in biliary gastritis, although there is little evidence this results in dysplastic changes. Gastritis can be found frequently after RYGB (when bile is less likely to reach the gastric pouch). However, recent histological studies of gastric pouch bile reflux found a similar incidence of bile reflux frequency, bile reflux index and Sydney system score when comparing 58 RYGB vs 64 OAGB/MGB patients.

Peter Small

H Pylori (HP) is a more important factor and may be a prerequisite for such changes to occur. It may be the increased incidence of gastric cancer after Billroth II gastrectomy for ulcer disease was due to H pylori infection. Eradication in HP positive patients before bariatric surgery would seem a sensible precaution, irrespective of operation type.

Reflux into the oesophagus of alkaline bile and the development of oesophagitis has not been shown to be a major problem following OAGB/MGB. Thus far, the data suggest that bile reflux into the oesophagus might even be reduced because of OAGB/MGB surgery.

Mr Small explained that there is no clearly identified, increased risk of carcinogenesis following OAGB/MGB although there is currently only 20 years of data from follow up after this procedure.  

“Approximately 50% of the population will get cancer now, and this risk is increased by obesity. Weight loss surgery has been shown to reduce cancer risk so we have to balance the risk of doing nothing or accept potential long term consequences of surgery. Upper GI cancer will occur inevitably in patients who have undergone all types of bariatric surgery. However, the evidence to date does not support the concern that cancer is caused by bile reflux into either the stomach or the oesophagus by itself,” Mr Small concluded. “Reported cases would appear to indicate that oesophageal carcinoma is actually more likely to be associated with restrictive procedures such as sleeve gastrectomy or gastric banding rather than the OAGB/MGB. Surgeons must be diligent in patient follow up and report cancer cases after all bariatric procedures.”

GERD and Barrett

Professor Maud Robert (France) began by stating that for many surgeons OAGB-MGB could potentially increase the risk of GERD and especially biliary reflux. Biliary exposure can lead to intestinal metaplasia (Barrett’s oesophagus) which is at risk of gastric/oesophageal carcinoma.

She said that a review of the literature showed that incidence of GERD in non-obese population ranges from 15 to 20% while it is estimated between 50 to 100% in obese individuals. Furthermore, long-standing GERD is responsible for oesophageal inflammation which heals in a metaplastic process with abnormal columnar cells (intestinal metaplasia or Barrett’s oesophagus) in up to 10% of the cases. In case of low-grade dysplasia, the risk of oesophageal adenocarcinoma is estimated between 0.5 to 13% /year and goes up to 5 to 20%/year in the presence of high-grade dysplasia.

Maud Robert

Therefore, she recommended that Barrett’s and GERD should be diagnosed prior to surgery with pre-operative upper GI endoscopy that could eliminate the risk of complicated GERD. Impedance Ph-studies should be used in case of symptoms of GERD, without esophagitis at endoscopy.

The length of the biliopancreatic limb has been implicated as a strong factor in malnutrition. Mahawar and colleagues have published several articles regarding the nutritional risk of a biliopancreatic limb that is too long when undertaking OAGB, suggesting not to exceed 150cm. However, unpublished data from Maude Le Gall, Paris Diderot University, France, showed a significantly increased concentration of bile acids when the biliary limb is shortened (publication in process). Therefore, shortening the biliary limb length could increase the risk of biliary reflux.

To treat GERD/Barrett’s effectively, lifestyle and medication therapy should be used as first intention, although weight loss via bariatric surgery is a main factor of improvement of GERD. To target acid reflux, histamine 2-receptor antagonists (H2RAs), proton pump inhibitors (PPIs) and sucralfate (miscellaneous GI agent) can be used. To target biliary reflux, several medications can be tried but with a mild efficiency including: ursodeoxycholic acid, bile acid sequestrants, PPI, Prokinetics and Baclofen.

“In the case of intractable GERD/Barrett’s after OAGB the literature seems to suggest that in case of severe reflux, in absence of malnutrition, a conversion to RYGB should be done whereas in case of malabsorption, in high risk patients, a reversal is preferred,” she added. “Roux-en-Y gastric bypass remains for many authors the gold standard in case of the presence of GERD or Barrett’s.

Hypoabsorption and protein-calorie malnutrition

Dr Scott Shikora (USA) said that the positive effects of OAGB/MGB are probably due to the longer length of the afferent limb, compared with the shorter biliopancreatic limb (BPL) of the RYGB. The longer the afferent limb, the greater the potential for protein-calorie malnutrition and nutritional deficiencies/complications. In addition, he added, that it is important to recognise that many patients present prior to surgery with nutritional deficiencies so patient screening of their biochemical markers should be performed.  This includes checking serum vitamin levels for B1, B6, B12, folate, iron, vitamin A, vitamin D, vitamin E, vitamin K, Zinc and albumin.

Scott Shikora

There are numerous nutritional deficiencies that can be seen after bariatric surgery. The macronutrients and micronutrients are absorbed in different locations along the gastrointestinal tract. The specific nutrients at risk for deficiency can be determined by which regions of the gastrointestinal tract are bypassed. These include water soluble vitamins (B vitamins, vitamin C), the fat soluble vitamins, (A, D, E, K), Calcium, Magnesium, Phosphorus, Sodium, Potassium) and the trace elements (Chromium, Copper, Fluorine, Iodine, Iron, Manganese, Molybdenum, Zinc, Selenium, and Cobalt). 

Since the ASMBS does not recommend OAGB/MGB is has no specific recommendations. However, a consensus paper on nutritional supplementation states that RYGB recommendation will likely work for OAGB/MGB patients. However, Dr Shikora advised that interested parties should follow the recommendations for duodenal switch patients. 

“Understanding the types of nutrient deficiencies that can occur, closely monitoring patients, and aggressively repleting those nutrient levels that are low, will reduce the likelihood of nutritional complications and poor outcomes,” he concluded.

To read the report from the first session, 'Fundamentals of OAGB-MGB' (part 1) of the report from the IFSO International Consensus Conference on OAGB-MGB, please click here

To read the report from the second session, 'Indications and Selection of Patients' (part 2) of the report from the IFSO International Consensus Conference on OAGB-MGB, please click here

To read the report from the third session, 'Technical Systematization' (part 3) of the report from the IFSO International Consensus Conference on OAGB-MGB, please click here

To read the report from the fifth session, 'Revision, Use as Revisional Surgery and Follow Up' (part 5) of the report from the IFSO International Consensus Conference on OAGB-MGB, please click here

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