MGB and one-anastomosis gastric bypass are on the rise

The MGB-OAGB 4th Annual Consensus Conference was held in Naples, Italy July 3-4, 2017 under the superb organisation of Professor Mario Musella, at a beautiful site on the Mediterranean seaside. The meeting was attended by 169 experienced surgeons from bariatric teams in 29 countries, where important studies were presented and discussed.

This article was authored by Mervyn Deitel, MD, SFASMBS, FACN, Director MGB-OAGB Club, Toronto, Canada

A French group reviewed their 2,014 MGBs; abscesses had occurred in 2.2% and were treated by endoscopic or percutaneous drainage, with no mortality. Methylene blue test has been important for operative detection of leaks. Revision for GE bile reflux or malnutrition was rarely necessary in the long-term. The operations were highly effective for excess weight loss. Studies suggested that the length of the bypassed limb may only influence weight loss in the early months after surgery. Bypasses of 150-250 cm were performed, depending on BMI and sociocultural conditions, but with the longer bypasses, total bowel length should be measured to be certain that 300 cm of common limb is left distally.

Figure 1: MGB with a long gastric pouch, starting from below the crow’s foot, and going proximally to the left of the angle of His. An anterior wide gastrojejunostomy is constructed 180-200 cm distal to Treitz’ ligament.

MGB or OAGB was performed safely as both a primary operation or a revision for failed gastric banding or sleeve gastrectomy (SG). Improvement in quality of life and co-morbidities resulted, with resolution of type 2 diabetes in >95%.

Cady of Paris, with 3,500 cases (using a 175-200 cm bypass limb), found that under-nutrition occurred in 1.5%, and if there is no quick result from replenishment, reversal is necessary to avoid death. The French group from Cornevarrieu-Toulouse reported that in their series of 2,400 patients with a 150-cm biliary limb, had 0.04% severe malnutrition (only 1 patient) requiring reversal. Weight loss after MGB-OAGB depends mainly on malabsorption. Malnutrition in patients in India (where 50% are vegetarian) is avoided by a bypass no greater than 200 cm and proper diet.

Figure 2: OAGB with long, narrow gastric pouch (15-18 cm) and an antecolic antegastric latero-lateral anastomosis between pouch and afferent enteric loop which is suspended ~8-10 cm above the anastomosis through an initial continuous suture which secures the afferent limb to the gastric pouch’s staple-line and with final fixation of the loop’s apex to the excluded stomach. Biliopancreatic limb averages 250-350 cm.

With the usual MGB gastric channel constructed 2-3 cm distal to the crow’s foot, bile GE reflux was negligible. The Kazakhstan group found that a longer gastric pouch significantly reduced postop bile reflux. Tolone’s group from Naples (S Tolone SOARD 2016), using multiple scientific studies, confirmed that GE reflux does not occur after MGB (unlike after SG which maintains the pylorus).

Carbajo of Spain and Luque-de-Leon of Mexico presented their outcomes from 2,850 OAGBs since 2002, with negligible bile reflux, marginal ulcer in <1%, and EWL and EBMIL >75%. Again, the OAGB was an excellent rescue after other failed operations. Long-term %EWL and co-morbidity resolution after OAGB were similar to the best results obtained with more aggressive and complex operations.

The importance of differentiating type 1 (auto-immune) diabetes (T1D) in the adult from type 2 diabetes was emphasised. Obesity can occur in type 1 if the patient takes excessive insulin, becomes hypoglycaemic, and then has to eat more (a vicious cycle). This can be controlled by dietary surveillance; if not, bariatric surgery for obese T1D will decrease weight, lower HbA1c, and lower insulin requirement. However, the T1D patient will always require insulin.

Unlike following other bariatric operations, carcinoma in the gastric channel or esophagus has not occurred. Some workers are performing robotic MGB, and note speed and technical ease.

A number of long-term studies comparing MGB-OAGB with SG and RYGB were presented. SG was followed by occasional serious high leaks, GE reflux, Barrett’s esophagus, and weight regain. Most MGB and OAGB surgeons had previously performed RYGB for many years. RYGB took longer to perform, was more complex, had longer learning curve, more marginal ulcers, increased internal hernias and bowel obstruction, more hypoglycemia, late weight regain and more difficulty to revise.

In comparison, MGB was relatively simple, rapid, safe, and had greater elevation of GLP-1, durable weight loss, ease of revision and reversal, and resolved GERD. With both RYGB and MGB, watch for iron deficiency anemia and hypoalbuminemia.

In many countries outside USA, MGB and OAGB have become the most common bypass operation for bariatric patients.