Mini-Gastric (one-anastomosis) Bypass Becoming a Mainstream Bariatric Operation
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The mini-gastric one-anastomosis bypass (MGB) was conceived by Dr. Robert Rutledge in USA 16 years ago, as a safe, rapid and effective bariatric operation. The MGB has slowly gained proponents throughout the world, particularly increasing in the past 5 years. In October 2012, an international MGB Conference of 55 experts was held in Paris, under the leadership of Drs. Rutledge and Jean-Marc Chevallier (President of the French bariatric society – SOFCO). Because of international requests, a second MGB Conference was held in Paris in October 2013, with 35 MGB surgeons from 13 countries, many at the professorial level.
The Chair of the 2013 Conference was Prof. Pradeep Chowbey, immediate Past-President of the International Federation for the Surgery of Obesity; many see Prof. Chowbey as the Father of both laparoscopic and bariatric surgery in India, where the MGB is being rapidly adopted following the excellent results reported by Kular and others. The MGB Consensus attendees all reported prior experience with other bariatric operations – Roux-en-Y gastric bypass (RYGB), gastric banding (GB) and sleeve gastrectomy (SG).
The laparoscopic operation (Figure 1) creates two components: first, a restrictive lesser-curvature gastric pouch; second, a 200 cm or longer jejunal bypass with a single antecolic gastro-jejunostomy (GJ) anastomosis, which leads to significant fat malabsorption.
Figure 1: Diagrammatic representation of the MGB (by Robert Rutledge)
Creation of the Gastric Pouch
The lesser curvature of the stomach is identified at the junction of the body and antrum. The stomach is initially stapler-divided at a right-angle to the lesser curvature, distal to the incisura (distal to the crow’s foot). A 28–40 Fr bougie is passed by the anaesthetist, and the stomach is stapler-divided upwards parallel to the lesser curvature. With approach to the gastro-esophageal (GE) junction, the surgeon divides the stomach lateral to the angle of His; the cardia in the MGB is explicitly avoided and not dissected (unlike in the SG operation).
Creation of the 200-cm Malabsorptive Jejunal Bypass
Attention is turned to the left gutter, and the omentum is retracted medially to identify the ligament of Treitz. The bowel is run to ~200 cm distal to Treitz’ ligament. At this site, the distal tip of the gastric sleeve is anastomosed antecolic end-to-side to the jejunum.
In the presence of a hiatal hernia, no effort is made to address this at the time of MGB. Experience has shown that MGB is very effective in resolving GE reflux disease (GERD). This is thought to be related to traction which the GJ anastomosis provides on the gastric pouch, which reduces the cardia within the abdomen, plus resolution of the patient’s obesity. We thus have a gastric conduit and a fat/carbohydrate malabsorptive procedure. The pouch in the MGB shows little dilation because there is no outlet narrowing by a stoma or pylorus.
Modifications of the Technique
Some (but not all) MGB surgeons vary the length of the bypass. In super-obese (or very tall) patients, the GJ is performed >250 cm distal to Treitz’ ligament. Tacchino’s group from Italy has performed >600 MGBs; Greco reported that recently they have modified the MGB by leaving a larger gastric pouch and constructing the GJ 300 cm proximal to the ileocecal valve (i.e. leaving a 300-cm common channel). Most of the surgeons agreed that the GJ must be placed at least 200-300 cm proximal to the ileocecal valve, to maintain adequate nutrition. Flores from Mexico presented the Spanish technique of Profs. Caballero and Carbajo, where an antireflux valve is constructed on the afferent side of the GJ; sutures are placed between the sleeve and afferent limb to inhibit reflux. Survey of the attendees revealed that >80% use the Rutledge method and measurements, 10% the Carbajo antireflux method, and 5% the Tacchino 300-cm common limb.
If ever necessary, the MGB can be modified for inadequate or excess weight loss by moving the anastomosis distally or proximally as a brief, simple procedure. Bhanderi of India constructs a longer sleeve, almost to pylorus. Prasad of India performs the MGB using robotics.
The MGB is now being performed for weight regain after the SG operation. All the experts emphasized that it is very important not to construct a short gastric pouch for the MGB. The MGB pouch is the opposite of the small proximal pouch constructed in the RYGB. A small, short gastric pouch in the MGB would recreate the physiology of the old Mason loop gastric bypass and could lead to bile reflux (as was done with some of Weiner’s earlier SG revisions to MGB). Presenters repeatedly emphasized the need for a long gastric pouch.
Survey Findings and Discussion
A SurveyMonkey® questionnaire had been carefully answered pre-Conference and was discussed. This is a largely academic surgical group who carefully records their data, because the MGB was met with some skepticism. The Survey identified a total of 16,651 MGBs performed by the attendees. Average preoperative BMI was 46.1 ±4.1 (SD) (range 38-62). Mean operating time was 80.3 ±24.9 minutes (range 38-130). Average hospital stay was 3.2 ±1.6 days (range 1.1-6.0), and became less as the surgeon performed more MGBs. Leaks were reported in 0.03% (5 patients), which are less than the dreaded proximal leaks following the SG operation.
During surgery, the use of the methylene blue or air test decreased with experience. The use of a drain also decreased with experience. Patients were usually ambulatory a few hours after surgery.
Diabetes had resolved at 1 year in 91.4 ±4.9% (range 82-96). Persistent resolution of co-morbidities and improvement in quality of life were reported by Peraglie based on a personal experience with 1,400 MGBs, Hargroder with 1,100 MGBs, Cady with 2,500 MGBs, Chevallier with 888 MGBs, Kular with 1,200 MGBs, Musella with 1,000 MGBs, Tacchino with 600 MGBs and W.J. Lee with >1,000 MGBs.
Preoperative GE reflux was found in 15.3 ±14.2%, and postoperatively in 4.7 ±14.2%. The experts’ opinion was that GERD improves after MGB. Revisional surgery has become necessary in 3.2% (0.4% for bile reflux). It was very rare that a Braun entero-enterostomy became necessary. Marginal ulcers have occurred in 1.4 ±1.8% (range 0-5), which is less than after RYGB. Interestingly, Spain and India have found almost no postoperative ulcer occurrence.
The %EWL was: 1 year 75.8, 2 years 85.0, 3 years 78.0, 4 years 75.0, 5 years 70.2, longer 70.0. Failure to lose >50% of excess weight at 5 years occurred in 14.2 ±25.1%. Operative 30-day mortality has been very low – 0.2% (33 deaths).
In the consensus survey, bowel obstruction was very rare and had occurred in 0.15 ±0.36% (range 0–1), and none was due to an internal hernia. There has been no intractable hypoglycemia.
Regarding marginal ulcer development, the MGB should not be performed in smokers, those taking salicylates, and many felt it should not be used in those taking heavy alcohol. However, Kular in India noted that patients in his area of India tend to take whisky, without problems. However, as with the RYGB, there is more rapid absorption of alcohol, which should thus be decreased.
Most of the surgeons prescribed a PPI, and all ordered supplements (multivitamins, calcium – preferably dairy, yoghurt, and Proferrin® as an iron supplement. In 5% of menstruating women, iron deficiency develops, and may require I.V. iron. The majority treat H. pylori preoperatively, and many treat it if it becomes necessary postoperatively. No case of carcinoma has been found in the gastric pouch or esophagus after MGB. Some critics have referred to a rat study where concentrated bile in the stomach led to cancer; however, J.D. Frantz in 1991 showed that bile led to hyperplasia and malignancy in the proximal 2/3 of the unique rodent stomach (which is squamous cell) and not in the glandular distal 1/3 (which corresponds to the human stomach).
Wei-Jei Lee of Taiwan described his 10-year comparison of MGB and RYGB, where long-term weight loss, resolution of diabetes and elevation of GLP-1 were slightly better after the simpler and safer MGB.
There was early prejudice against the MGB by surgeons who performed a longer, more difficult procedure. However, the numerous surgeons throughout the world who perform the MGB reported essentially the same results. The attendees have found the MGB to be a rapid, technically simple, safe, effective operation with an absence of leaks, a single antecolic large anastomosis in easy view, the bypassed length modifiable with the degree of BMI, durable weight loss, easily revisable by moving the anastomosis, and if ever necessary, reversable.
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