Laparoscopic Mini Gastric Bypass
Laparoscopic Mini Gastric Bypass Surgery
The mini gastric bypass is also known as the one-anastomosis gastric bypass. It is a modification of the standard Roux-en-Y gastric bypass. The gastric pouch is long and thin and there is only one join with the intestine made rather than two in a Y-shape configuration.
How does it work?
It was created to reduce operating time and reduce complication rates. Operating time has been proven, operation complication rates show a trend of being reduced though not to the level of proof.
Unexpectedly a number of studies have shown improved weight loss with the mini-bypass when compared to the standard roux-en-y gastric bypass. The exact cause of this is unknown though is thought to be related to the length of intestine left between the stomach and the new join. Recent studies in roux-en-y gastric bypass where this length is long have also shown benefits over conventional surgery.
Why was the Mini-gastric bypass created?
The mini gastric bypass works through restriction, malabsorption, reduced hunger, and improved satiety (the feeling of fullness) in ways pretty much identical to the roux-en-y gastric bypass.
Perioperative care pathway
The pre-operative preparation for mini gastric bypass is identical to that of the roux-en-y gastric bypass with education sessions with our Dietitian, Nurse specialist, and Anaesthetist. There is a three-week Optifast diet leading up to your surgery date.
The operation is performed under a general anaesthetic. The laparoscopic approach is successful in most patients though like the other operations occasionally conversion to open is required. There are generally five small incisions made for the instruments (same as other operations ). The operation takes approximately 1 to 1.5 hours (slightly shorter than the roux-en-y gastric bypass and slightly longer than the sleeve Gastrectomy).
Recovery is pretty much identical to that of the sleeve Gastrectomy and roux-en-y gastric bypass with two nights in hospital, a progressive diet over six to eight weeks, and the recommended two weeks off work. Physical activity is encouraged immediately after surgery though should be light (short walks) but increased over time. By two weeks most light activities should be easily performed. We recommend waiting four weeks for heavy lifting and strenuous activities. Follow-up appointments are as per the sleeve Gastrectomy.
The complications are mostly the same as for roux-en-y gastric bypass, with a trend to slightly lower risks of bleeding and leak at the joins. The mini-gastric bypass carries a small additional risk of symptomatic bile reflux. Bile which is one of the digestive juices is free to enter the stomach in the mini gastric bypass. For most people this is not a problem though for a small number of people this causes significant discomfort. If the symptoms are bad then an additional operation is required to change the mini-gastric bypass to a roux-en-y configuration.
A meta-analysis (pooling of many papers) can be read here
The key findings of the study are:
- Lower leak rate with mini bypass (0.7% vs. 2.2%)
- Overall no difference with early complications but lower late complications with the mini bypass (0.5 vs. 1.6%)
- Greater weight loss at 1yr by 17kg with the mini bypass but drops to only 4kg difference at 5yrs
- Greater resolution of many co-morbidities with the mini bypass including high blood pressure, type 2 diabetes, obstructive sleep apnoea
- Greater resolution of osteoarthritis with the sleeve Gastrectomy
- Increased ulcer rate with the mini bypass
- Lower Gastroesophageal reflux rate with the mini bypass
- Greater revisional surgery with the sleeve Gastrectomy (1 vs. 7%)
This study is made up of many smaller studies which gives the study more strength but many of the studies were small with less than 100 patients in them. Most of the studies were conducted during the era when only enthusiasts were doing the operation so it wasn’t a mainstream operation at the time. This means these results may not be fully reflective of what the true outcomes are. Typically early results of a new procedure over-estimate the positive outcomes and down-play the negatives. Most importantly these studies do not report on quality of life outcomes like food enjoyment and side-effects like dumping syndrome and bile reflux symptoms.
Mini gastric bypass is one of the most recently developed weight loss operations and as such has had less time for long-term evaluation than either the gastric bypass or the sleeve Gastrectomy. This sort of surgery is for life so it is important to ensure it is safe and effective over a long period of time. There were two initial concerns when the mini gastric bypass first came out, firstly the development of bile reflux syndrome and secondly the potential to cause oesophagogastric cancer.:
Bile reflux:
Bile reflux (bile entering the stomach and or oesophagus) is a normal occurrence in many people who have not had any gastric surgery. In a small number of people, it is thought to be a cause of upper abdominal symptoms such as discomfort, indigestion, and reflux/retrosternal burning. The incidence of bile reflux is significantly increased after the mini gastric bypass as bile is free to enter the stomach pouch at the intestinal anastomosis. Not all people with bile reflux are symptomatic though and there are no large studies to determine how many are symptomatic mini gastric bypass. Quoted figures range from 8-55% though most symptoms are mild and most centers report very low rates of needing to perform revisional surgery for bile reflux.
Gastroesophageal cancer:
Rutledge performed the first mini gastric bypass procedure in the United States of America in 1997. Since then the numbers of this procedure performed each year has rapidly increased and tens of thousands are performed globally each year. To date, there has been no report of increased development of Gastroesophageal cancer in patients undergoing the mini bypass. This may be because it does not cause cancer or it could be because it takes more time to develop the difference. Most doctors now think it is because it does not cause cancer as the reason for concern originally came from studies in animals, not humans and no studies have conclusively shown that bile reflux causes Gastroesophageal cancer in humans.