First performed in the United States in 1997 by Dr. Robert Rutledge,1 Mini-Gastric Bypass surgery is a modification of the conventional gastric bypass surgery. Many surgeons have completed this surgery successfully, and it may be a total replacement for the traditional gastric bypass surgery due to its relative advantages. However, its potential complications have discouraged few surgeons from this procedure.1
The mechanism of gastric bypass surgery is still a combination of food restriction and malabsorption. The indications and contraindications are nearly the same. The result/outcome is similar to that of the conventional gastric bypass. The significant difference is in the surgical procedure.
Procedural differences between Mini and Roux-en-y Gastric Bypass
The conventional gastric bypass surgery is done by creating a pouch out of the stomach. This pouch is about 30mls, and it serves as the definitive stomach while the remaining stomach is bypassed. About 45cm from the bypassed stomach, the small intestine is divided, and the lower end is anastomosed (connected) to the pouch (gastrojejunostomy). The upper end is then anastomosed to the small intestine at about 100cm from the pouch (jejunojejunostomy).
Therefore, the partially digested food moves from the pouch into the small intestine passing through about 100cm of the small intestine without mixing with the pancreatic enzymes and bile. The food, the pancreatic enzymes, and the bile come in contact at the jejunojejunostomy after passing through about 145cm of the small intestine. This portion of the small intestine is therefore excluded from meaningful chemical digestion and absorption.
In Mini-Gastric Bypass, the stomach pouch is created in a way that resembles a sleeve as in gastric sleeve surgery. A loop of the small intestine (at about 200cm from the bypassed stomach) is then connected to this sleeve-shaped stomach. The pancreatic enzymes and the bile pass through approximately 200cm of the small intestine before coming in contact with the food. Thus, 200cm of the small intestine (as opposed to 145cm in conventional gastric bypass) is excluded from meaningful chemical digestion and absorption.
Mechanism of weight loss in Mini-Gastric Bypass
The sleeve-like pouch has limited capacity and only accommodates a small amount of food leading to an early sensation of fullness while eating. Also, the exclusion of about 200cm of the small intestine from absorption leads to significant weight loss.
Indications for Mini-Gastric Bypass surgery
This procedure has similar indications as other weight loss surgeries. A Body Mass Index (BMI) higher than 40kg/m2 or 35kg/m2 in the presence of any obesity-associated disease conditions are significant indications for gastric bypass surgery. All obese people who have been unsuccessful in achieving satisfactory weight loss following non-surgical methods can also benefit from Mini-Gastric Bypass surgery.
The effectiveness of Mini-Gastric Bypass surgery
The weight loss outcome and resolution of comorbid conditions after Mini-Gastric Bypass surgery have been shown by various studies to be comparable or even superior to those of conventional Roux-en-Y gastric bypass surgery. Mini-Gastric Bypass surgery also has additional benefits including a shorter operative time and fewer major complications.2
In a study conducted by Lee et al. the percentage excess weight loss for Mini-Gastric Bypass five years after surgery was 72.9% and average BMI was 27.7kg/m2. These were better than percentage excess weight loss of 60.1% and average BMI of 29.2kg/m2 in patients who had Roux-en-Y gastric bypass.2
This finding is also similar to another study by Lee et al. where the percentage excess weight loss was more significant in Mini-Gastric Bypass group than in Roux-en-Y gastric bypass group one year post-surgery 64.9% vs. 58.7% respectively. However, this difference became insignificant two years after surgery.3
Regarding resolution of comorbid conditions, a systematic review of many studies by Quan et al. revealed that patients who had Mini-Gastric Bypass had a better remission of type 2 diabetes when compared to those who had either gastric sleeve or Roux-en-Y gastric bypass.4
Complications of Mini-Gastric Bypass surgery
These are fewer but similar to those of conventional gastric bypass surgery. Lee at al. reported a complication rate of 7.5% after Mini-Gastric Bypass, a value that is far below that of Roux-en-Y gastric bypass (20%).2 The following are worthy of note:
Esophageal and gastric cancer
The loop configuration of the small intestine in addition to bile acid reflux was thought to expose the stomach and esophageal lining to bile acid. However, no concrete evidence to support this assumption, and no reported case of esophageal cancer following Mini-Gastric Bypass. The only case of gastric cancer that was reported after Mini-Gastric Bypass was not found in the pouch but the bypassed stomach.1
Gastro-esophageal reflux disease (GERD)
Gastric bypass surgery is known to improve symptoms of heartburn or regurgitation, and this has been found to be similar in both Mini-Gastric Bypass and Roux-en-Y gastric bypass.
Internal hernia/intestinal obstruction
This is very rare following Mini-Gastric Bypass as opposed to Roux-en-Y gastric bypass surgery where the incidence can be as high as 6%.1
Summarily, Mini-Gastric Bypass surgery is an effective weight loss surgery with an outcome that is similar to traditional gastric bypass. Eligibility for the operation and mechanisms of weight loss are the same, but complications are fewer. The most dreaded complication of esophageal/stomach cancer has not been substantiated.
References
- Mahawar KK, Kumar P, Carr WR, et al. Current status of the mini-gastric bypass. Journal of Minimal Access Surgery. 2016;12(4):305-310. doi:10.4103/0972-9941.181352.
- Lee WJ, Ser KH, Lee YC, Tsou JJ, Chen SC, Chen JC. Laparoscopic Roux-en-Y vs. mini-gastric bypass for the treatment of morbid obesity: A 10-year experience. Obes Surg. 2012;22:1827–34
- Lee W-J, Yu P-J, Wang W, Chen T-C, Wei P-L, Huang M-T. Laparoscopic Roux-en-Y Versus Mini-Gastric Bypass for the Treatment of Morbid Obesity: A Prospective Randomized Controlled Clinical Trial. Annals of Surgery. 2005;242(1):20-28. doi:10.1097/01.sla.0000167762.46568.98.
- Quan Y, Huang A, Ye M, et al. Efficacy of Laparoscopic Mini Gastric Bypass for Obesity and Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis. Gastroenterology Research and Practice. 2015;2015:152852. doi:10.1155/2015/152852.
