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IFSO Consensus Conference on OAGB-MGB

IFSO International Consensus Conference on OAGB-MGB (part 3)

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 third session - Technical Systematization.

Module III: Technical Systematization

Position of the patient and set of trocars

Lilian Kow

Incoming IFSO President, Dr Lilian Kow (Australia) began by stating that laparoscopic bariatric surgery usually takes at least an hour and may, in difficult cases, take several hours. Therefore, patients with severe obesity are vulnerable to position-related injury whilst on the operating table as a result of their size and the length of the procedure. For this reason, it is fundamental the correct bariatric-weighted operating table is utilised so the operator has the ability to adjust the position, evenly distribute the body pressure preventing pressure injuries and transfer patients to and from the operating table.

She added that most laparoscopic bariatric procedures use one of two operating positions, namely, supine with legs adducted and supine with legs abducted (French position). The modified lithotomy position is not recommended. Although the reverse Trendelenburg position is typically used for laparoscopic bariatric surgery, risks to a patient in this position include deep vein thrombosis, sliding and shearing, perineal and tibial nerve injuries.

“The positioning of the trocars varies but carry the principles of triangulation and directed at the field of surgery i.e. the stomach and the ability to bring a loop of small bowel for the anastomosis,” she added. “It is usual to require 4-5 trocars for the procedure and 12mm trocars are required for insertion of staplers.”

Pouch formation

Dr Mohit Bhandari (India) said that gastric pouch in a mini bypass is 18-20 cm long on a stretched bougie and around 12-16 cm above the anastomoses with a 3cm width.

Mohit Bhandari

A harmonic shear creates the space by dissecting the omentum fat below the incisura at least 1.5-2cm.  A horizontal fire is performed with a gold reload below the incisura angularis from the right-sided 12mm port and subsequent firing is done with the blue loads to create a vertical pouch all along the 36 fr bougie.

In order to avoid the dissection at the lest crus, retro gastric dissection is performed close to the angle of his to take down the short gastric vessels and space is created to avoid injury to the gastroesophageal junction.

Dr Bhandari creates a long pouch to minimise reflux into the oesophagus, however, he noted that there are no studies that have determined the minimum length of the pouch to minimise reflux in the oesophagus. Although his own studies revealed that there is routine bile reflux (<40%) in the pouch, it appears to be inconsequential. In addition, bile reflux in the oesophagus is seen in about 3% of the cases and oesophagitis more than grade A in 21% of cases.


Dr Leonardo Emilio da Silva (Brazil) stated that despite the excellent MGB/OAGB results, there are many criticisms related to the occurrence of enterogastric biliary reflux and especially entero-oesophageal. The key difference between the MGB/OAGB and the classic Billroth II reconstruction is the length MGB/OAGB (>150cm) of the afferent loop – the length determines that the bile that reaches the gastric pouch is less aggressive than the bile content of a 30-40cm afferent limb of Billroth II.

He said that there are some basic differences between the MBG surgery proposed by Rutledge and the OAGB proposed by Carbajo, the main differences are the extent of gastroenterostomy and the anti-reflux mechanism that Carbajo proposes.

Leonardo Emilio da Silva

OAGB proposes that the entire small intestine is measured before determining the size of the biliopancreatic loop, which is not necessary for MGB. The lift of the enteric loop must be made antecolic and antegastric, isoperistaltic and can be done via the passage of a drain through the mesentery, below the jejunal arch with the traction of the loop by means of a clamp tractuating the drain cranially.

Although, Carbajo proposes that the gastrojejunal anastomosis be performed on the anterior wall of the gastric pouch, in his clinical experience Dr da Silva has not observe any difference between the two modes, but believes that the posterior anastomosis is more functional and allows better emptying of the gastric pouch and consequently determines a better clearance of a possible biliary content.

“The gastroenterostomy should be latero-lateral, posterior, non-stenotic, measuring 30-35mm and we believe that the anti-reflux tactic of the anterior seromuscular plane of the anastomosis is fundamental to minimize the passage of the biliary flow to the Interior of the gastric pouch,” he concluded.

Staple/cartridge recommendation and staple line reinforcement

Dr Laurent Layani (UAE) began by stating that at times the difference between does not translate into any actual difference in clinical practice. To demonstrate this, he cited a study comparing the iDrive (Medtronic) and Echelon (Ethicon) in sleeve gastrectomy procedures.

Laurent Layani

All procedures were performed by the same surgeons and with the same technique, and agreed on the definition of bleeding. If bleeding was determined, an endoclip was applied and at the end of the procedure the number of endoclip was counted. The results showed that more endoclips were used in Echelon patients (BMI40.44.9, 50.63% vs 38.96% and BMI45-49.9 56.66% vs 32.14%). He explained that minor bleeding from the neo greater curve not uncommon and the use of more endoclips in the Echelon was of no clinical significance.

Regarding staple line reinforcement, there is no consensus and its use remain controversial. However, the consequences of not using staple line reinforcement can be costly for the patient (sepsis, organ failure, extended hospital stay). There are currently several options including fibrin glue, suture oversewing and buttressing (non-permanent, synthetic, tissue), however the are a lack of studies and contradictory data reported in the literature.

“The literature concerning staple line reinforcement is inconclusive and although the complication rates are low, most studies small, retrospective and underpowered,” concluded Dr Laurent Layani. “The meta-analyses are from small retrospective studies and few studies have compared different buttress materials or techniques. We need further studies to provide consensus on indications, staple cartridge, staple line reinforcement and operative technique. At the moment, all of this depends on your location, healthcare service and on the economic situation as to which devices surgeons use.”

Defining limb lengths

Discussing the importance of limb length, Professor Kamal Mahawar (UK) said that over the last few decades it was thought RYGB worked through a combination of restriction and malabsorption. The idea that malabsorption made an important contribution to weight loss led to surgeons attempting to maximise the benefits of this procedure by prolonging the limb lengths and development of the so-called ‘distal gastric bypass’.

Kamal Mahawar

However, it was not until recently it became obvious that malabsorption accounts for only 11.0% of the total calorie deficit in the short term after RYGB and possibly even less in the long term. At the same time, it was discovered that most of the benefits of RYGB can be obtained with a combined alimentary limb and biliopancreatic limb of 100-200cm.

“The experience with RYGB which suggests that bypassing more than 150cm of small bowel is not associated with significantly improved clinical outcomes;  and data reporting significantly increased rates of nutritional complication with longer biliopancreatic (> 150 cm) with OAGB have led us to conclude that the optimum length of biliopancreatic limb with OAGB should be no longer than 150cm and possibly even shorter, given that all of the small bowel is placed as metabolically more effective biliopancreatic limb,” he concluded.

Closure of the mesenteric space in OAGB-MGB

Salman Al Sabah (Kuwait) said one of the perceived advantages of an OAGB-MGB is the avoidance of needing a jejuno-jejunostomy and the presumptive absence of an internal hernia (IH), with only four cases of IH reported to date, including Petersen’s Hernia, described during the 1900s by Dr Walther Petersen, as a hernia that protrudes through the Petersen’s space (PS), which is formed by the Roux loop and the transverse mesocolon. This has led some authors to maintain that the closure of the only defect created during an OAGB-MGB is not mandatory.

Salman Al Sabah

However, given the growing popularity of this procedure, investigating dangerous complications that may arise from it is very important. Globally, more than 30,000 OAGB-MGB have been performed, translating into an approximate incidence of 2/10,000 published cases and 6/30,000 published as well as unpublished cases of Petersen’s Hernia.

Therefore, it would appear the incidence of Petersen’s Hernia is approximately 1:5000, compared to RYGB, which has an incidence of Petersen’s Hernia of 0.9–5%. However, as there have only been four published reports on this topic and therefore, it can be thought that this low approximated incidence is true, explained Dr Al Sabah. However, he cautioned that if a patient presents with vague, non-explained abdominal pain, this should raise a suspicion of IH.

“The relatively low incidence of internal hernias after MGB/OAGB might explain why none of the large series till date have reported any Internal Hernia (IH)/Petersons Hernia (PH) with OAGB-MGB and a long pouch and large Petersen’s space with OAGB-MGB helps reduce the incidence of PH with OAGB-MGB,” concluded Dr Al Sabah. “Therefore, because it is such a rare condition, we do not believe routine closure of Petersen’s space with OAGB-MGB can be recommended at this stage.”

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 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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