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IFSO Consensus Conference on OAGB-MGB

IFSO International Consensus Conference on OAGB-MGB (part 1)

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.

In May 2018, the International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO) published a position statement safety and effectiveness of the mini gastric bypass-one anastomosis gastric bypass (MGB/OAGB) procedure (De Luca M, Tie T, Ooi G, Higa K, Himpens J, Carbajo MA, Mahawar K, Shikora S, Brown WA. Mini Gastric Bypass-One Anastomosis Gastric Bypass (MGB/OAGB)-IFSO Position Statement. Obes Surg. 2018 May;28(5):1188-1206). The position paper was the conclusion from an IFSO commissioned task force asked to determine if MGB/OAGB is an effective and safe procedure and whether it should be considered a surgical option for the treatment of obesity and metabolic diseases.

It was also decided by the task force that the panel’s consensus recommendations would be based on a combination of formal consensus development approaches, including the Delphi Method. Subsequently, the Consensus Organization and Scientific Committees selected an Expert Panel who are worldwide representatives of the bariatric/metabolic surgical experience with OAGB-MGB and invited them to attend the IFSO International Consensus Conference on One Anastomosis Gastric Bypass (OAGB-MGB), based on their active performance of a pre-determined experience with the different procedures in bariatric/metabolic surgery, particularly with OAGB-MGB.

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 first session - Fundamentals of OAGB-MGB.

Fundamentals of OAGB-MGB

The history of MGB and OAGB

The first presentation from Kuldeepak Kular (India) stated the first ‘Mini Gastric Bypass’ (MGB) procedure in September 1997, when Dr Robert Rutledge (a trauma surgeon at University Hospital, North Carolina) operated a multiple gun-shot wound abdomen. The final reconstruction in this patient gave him the idea of the MGB. The reconstruction was similar to the old Bilroth II, but with a longer and narrower stomach pouch (Figure 1).

Figure 1: Mini Gastric Bypass with a longer and narrower stomach pouch

In 2000, Dr Rutledge presented his MGB data at the Annual meeting of the ASBS (now called ASMBS). A lot of controversy was generated as many saw the MGB as the same old Mason’s loop bypass which would result in bile reflux and dangerous leaks.

In 2005, Dr Eric Demaria from the University of Iowa, published a paper on the complications and conversions of the MGB to RYBG in 32 patients from five different hospitals in North Carolina (DeMaria et al, Surgical revision of loop (“mini”) gastric bypass procedure: multicenter review of complications and conversions to Roux-en-Y gastric bypass, Surg. Obes. Relat. Dis. 3 (2007) 37–41). However, most of these ‘short pouch’ operations were performed by Dr Steven Olchowski - who had not trained with Dr Rutledge. Due to the controversy, Dr Rutledge halted his practice and was invited to go around the world to educate colleagues on the correct MGB technique.

Overtime, more and more MBG papers were published some demonstrating that the long-term results showed superiority of the MGB over the Sleeve Gastrectomy and Roux en Y Gastic Bypass (RYGB) operations in terms of safety, quality of life, durability and the ease of revision.

Kuldeepak Kular

In 2002, Professor Miguel Carbajo (Spain) started performing a modified version of MGB after reviewing Dr Rutledge’s publications. The modification was raising an 8-10cm afferent loop sutured to the lateral wall of the gastric pouch to decrease the reflux by gravity (Figure 2). Rutledge was invited by Carbajo in 2004 to the annual conference of the Spanish Society of Obesity, where the two versions of these bariatric procedures were presented. Carbajo named his modification One-Anastomosis Gastric Bypass (OAGB) or Bagua (Bypass Gastrico de una Anastomosis).

Figure 2: OAGB- One Anastomosis Gastric Bypass by Carbajo

In August 2012, the first MGB/OAGB consensus meeting was held under the leadership of Drs Rutledge, Kular and Deitel in Paris and again in Paris in October 2013. In 2014, IFSO held the first MGB/OAGB Course in Montreal during the IFSO annual Conference and the following year, the MGB Conclave was held in New Delhi organised by Drs Arun Prasad and Kuldeepak Kular. At the 2015 MGB/OAGB meeting in Vienna, the MGB/OAGB Club was officially formed under the Presidentship of Dr Kular with Dr Deitel as Director and Dr Rutledge as the Honorary President. The MGB/OAGB Club now has meetings every year.

In 2018, IFSO’s position statement recognised the procedure as the main stream bariatric operation however, IFSO suggested dropping the name MGB and continue with only OAGB, but, controversy over the name still remains.

Controversy over the denomination: MGB or OAGB

In the next presentation, Dr Mario Musella (Italy) outlined how Dr Rutledge’s MGB procedure differed from Dr Mason’s loop gastric bypass with one anastomosis:

  • The Mason’s loop bypass provides a gastric pouch wide and short with a horizontal shape, thereby exposing the oesophageal mucosa to reflux of caustic bile coming from the biliopancreatic limb
  • In the MGB procedure the gastric pouch is obtained by dividing the stomach (starting with a perpendicular firing at or beyond the Crow’s Foot about 3-4cm proximal to pylorus) at the junction of the body and antrum (where the jejunal loop can be brought up comfortably) and the distal end of the gastric tube anastomosed antecolic to the side of the small bowel at 200cm distal from the ligament of Treitz

Mario Musella

Dr Musella explained that the gastric pouch should be fashioned long and narrow, stapling about 1 cm away from the bougie and leaving some fundus and surgeons should avoid the EG by about 1-2cm.

He then outlined some of the differences between the MGB and the ‘anti-reflux’ technique (OAGB), developed by Drs Carbajo and Caballero (Spain), including:

  • The OAGB has a latero-lateral anastomosis between the loop of jejunum and the pouch, and the division of the gastric pouch was started horizontally
  • The jejunum is fixed to the staple-line of the gastric pouch with 6-10 sutures
  • The whole small bowel shold be measured and the midportion for the gastrojejunostomy is selected.
  • Lengths of biliopancreatic and common limb are usually similar (from ∼250 to 350cm) and for increasing BMIs, 10–50 cm of bypassed small bowel (with no specific formula) are added
  • The common channel is always maintained at least ∼250–300 cm

Dr Musella concluded by stating that MGB and OAGB are not the same procedure with some variations on the length of the limb and pouch. However, they are in the same class of procedure (pre-piloric single anastomosis gastric bypass) and maintaining the MGB/OAGB definition aids academic acknowledgement, bibliographic research and the identification of hybrid procedures, in which surgeons pick the best from both MGB and OAGB.

Worldwide numbers of bariatric procedures and OAGB-MGB

IFSO President, Professor Almino C Ramos (Brazil) then outlined how the number of OAGB-MGB procedure have risen dramatically over the last few years and although sleeve gastrectomy is still the most performed procedure, only MGB/OAGB (5% in 2016) and revisional procedure are increasing, all the other are decreasing (Angrisani L, Santonicola A, Iovino P, Vitiello A, Higa K, Himpens J, Buchwald H, Scopinaro N. IFSO Worldwide Survey 2016: Primary, Endoluminal, and Revisional Procedures. Obes Surg. 2018 Dec;28(12):3783-3794). However, the rise in the number of MGB/OAGB procedures has not been universal with some countries (United Kingdom, Israel, Egypt, Switzerland, Australia, Argentina) adopting the procedure more than others (In USA OAGB-MGB continue as not reported).

Almino Ramos

Citing data from the forthcoming 5th IFSO Registry Report (2019), Professor Ramos revealed that there is evidence that the MGB/OAGB is effective in patients with super obesity and the procedure has better weight loss than RYGB and sleeve gastrectomy. Despite such advantages, further research is required as the data also revealed that post-operative MGB/OAGB musculoskeletal pain increase.

“MGB/OAGB procedure is an establish procedure, not only are the numbers of procedures are increasing, but so are the number of research paper, which increased by 31% in 2018,” concluded professor Ramos. “The name MGB/OAGB is not a black or white issue, the mechanism/s of the procedure is the issue that we really must understand.”

Guidelines from the International MGB/OAGB Club

Dr Karl Rheinwalt (Germany) then presented the outcomes of a questionnaire that was sent to MGB-OAGB Club members (59 responders) concerning the procedure.

Karl Rheinwalt

The key findings were:

  • Bougie size between 34 and 40mm with no variation of bougie size with age and BMI
  • No standard use of staple line reinforcement
  • Size of the gastrojejunostomy 45mm
  • No routine splitting of the greater omentum
  • No routine closure of Petersen´s space
  • No routine measuring of total bowel length, minimum BMI-cutoff 25-30 in non-obese diabetic patients
  • Routine simultaneous closure of large hiatal hernia (>5cm)
  • Conversion to RYGB in cases of severe postoperative reflux
  • Postoperative routine prophylactic PPI-cover for 3 to 6 months
  • Life-long supplementation with multivitamins, calcium, iron, vitamin D and three monthly vitamin B12 injection
  • Bypass-lengthening as the most appropriate option in cases of severe weight regain

OAGB-MGB: The positive aspects

Professor Miguel Carbajo (Spain) said that bariatric surgery should have minimal risk of complications and lead to substantial durable weight loss, eliminate or ameliorate comorbidities, improve quality of life, and lengthen life expectancy. Both MGB and OAGB share a long gastric reservoir and only one anastomosis. However, there are several differences between MGB and OAGB:

  • In MGB no routine total small bowel (SB) counting, but establishing a fixed bilio-pancreatic limb length
  • OAGB (with its higher hypo-absortive component due to longer biliopancreatic limb length after having measured the total SB length) may even be compared with the more complex bilopancreatic diverting procedures

Miguel Carbajo

Professor Miguel Carbajo summarised that OAGB-MGB is technically simpler than RYGB and biliopancreatic diverting procedures and thus carries less perioperative risks, leading to a shorter learning curve and other benefits such as short operative time, rapid mobilization, short hospitalization, less perioperative complications and even few re-admissions. As the procedure is less complex, it is a highly reproducible and adaptable procedure, and suitable for special subgroups such as those at with extreme BMIs and age (11-13).

“OAGB-MGB is indeed a superb and simple option to revise other fully restrictive or mixed failed procedures, conversion from sleeve gastrectomy to OAGB-MGB may become the most common revisional operation in the next years,” he concluded. “OAGB-MGB is a safe and effective powerful alternative, but standardising teaching and performance is mandatory to avoid violating its basic principles.”

OAGB-MGB: The negative aspects

Current president of the ASMBS, Dr Eric DeMaria (USA) focused on why the ASMBS has not endorsed the OAGB/MGB procedure, he said that although he has never performed an MGB/OAGB procedure and only written one paper on the subject, he did work at the University Hospital affiliate in North Carolina, where Dr Robert Rutledge carried out an early series of MGB operations.

The vast majority of surgeons in the United States have similarly never done this operation as it was discredited by Mason and others early in the development of gastric bypass in favour of the Roux-en-y. Early in the development of this operation, there were 32 patients from five different tertiary hospitals in the region where the procedure originated who required revisional procedures due to complications (bile gastritis, ulcers, malabsorption/malnutrition etc). He suspected that there were more patients who had revisions who were not identified, but their circumstance had changed (moved away, change insurance coverage etc). 

Eric DeMaria

Recent follow up discussions with the original five centres that contributed revision cases to the original series suggests at least 30 more patients have undergone revision of OAGB-MGB for complications, mostly related to bile reflux, at those centres in the past 5-10 years.

Dr DeMaria explained that there are very few malabsorptive procedure in the USA (~1%) and managing these patients is more complex compared with restrictive procedures. He said that there are concerns that MGB/OAGB may ultimately be associated with oesophageal cancer due to bile reflux.  Given the tremendous scrutiny that exists in the United States along with the ‘black eyes’ of the past, in which American surgeons supported doing operations that were ultimately discredited and abandoned (including JI bypass, vertical banded gastroplasty, various forms of gastroplasty, gastric banding and LAGB), the ASMBS must be very cautious with its endorsements.

The ASMBS, he said, has adopted a stringent accreditation process that has contributed to the reduction of mortality and complication rates from bariatric surgery procedures nationally. Furthermore, the Society’s new procedure endorsement process considers patient safety as paramount in the robust and detailed assessment of novel procedures for the highly- coveted endorsement of the ASMBS.

As for concerns about the potential for malignancy due to bile reflux, DeMaria noted that the OABG/MGB procedure leads to cancer in animal models, and that this impact is likely due to duodenogastric reflux including bile.  Furthermore, a review of studies of foregut cancers believed due to bile reflux arising after previous gastrectomy for benign disease (e.g. ulcers) revealed that the average interval between gastrectomy and subsequent malignancy is at least 20 years, but more likely 30-35 years. 

“We simply do not know the 30 year follow up on the OAGB/MGB,  If the FDA were to consider a new medication that demonstrated an increased risk of cancer in pre-clinical animal models, they would require the labelling to include a warning about potential long-term risk for malignancy. At this point the OAGB should come with a warning on its “label” regarding potential long-term risks based on both pre-clinical animal data and retrospective human data in similar anastomotic procedures,” he concluded. “More long-term human data is needed to alleviate this concern.”

OAGB-MGB: The experience changed my mind

Mal Fobi (USA/India) said that by 2010, he had come to the conclusion that the two best bariatric operations were BPD-DS and banded-GBP for treatment of patients with severe obesity. However, the following year he saw Drs Rutledge and Kular presented their MGB outcomes and their findings did not match the controversial perceptions of the Rutledge MGB held in the USA based on the Johnson/Demaria article. He also noted similar results from the OAGB operation, technically the same as MGB, except for the anti-reflux sutures. The outcomes from both procedures were not reflective of the perception within the ASMBS.

In 2016, Dr Fobi was hired as a consultant at Mohak Bariatric and Robotic Surgery Center (MBRSC), in Indore, India, and evaluated the outcomes from 2,765 MGB/OAGB procedures. He reported that:

  • Comparative evaluations between the MGB/OAGB and the GBP, MGB/OAGB and the SG and MGB/OAGB and BGBP, showed that the incidence of anaemia, hypoproteinaemia and hypovitaminosis was slightly higher than in the gastric bypass
  • There were three documented revisions to gastric bypass because of bile reflux and five cases of revision because or either excessive weight loss or hypoproteinaemia
  • Two cases of intractable diarrhoea were treated by revision operation
  • No mortality from protein caloric malnutrition from 4,500 procedure
  • The incidence of protein deficiencies was less than with BPD and/or BPD-DS
  • The incidence of anaemia and marginal ulcers were not significantly higher than in the regular GBP.
  • The incidence of bile reflux and de novo reflux for OAGB-MGB was less than reported after the SG.

MAL Fobi

“Having done more than seven thousand gastric bypasses, open and by laparoscope, and another 3,000 other bariatric operations, I can categorically state that the MGB/OAGB is technically a simpler operation to perform than a sleeve gastrectomy, a gastric bypass or a BPD-DS particularly in patients with super obesity and super-super obesity. The scientific parameters devoid of all the personalities and political conflicts made up my mind about the superiority of the MGB/OAGB,” he added. “The MGB is better than the banded bypass and that is a hard thing for me to say!”

There are relative contraindications to the MGB/OAGB such as cirrhosis, GERD, large hiatal hernia, severe inflammatory bowel disease, class 1 and II obesity, heavy smokers, patients with  H/O PUD, inability to follow the patient after the operation and patients not likely to take their supplements after surgery.

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 fourth session, 'Complications/Controversies: Diagnosis, Treatment and Prevention' (part 4) 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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