One anastomosis gastric bypass
How the surgery works
The surgeon creates a long stomach pouch, similar to the pouch created during sleeve gastrectomy. The new stomach pouch is then connected to part of the small intestine through an opening called an anastomosis.
This means food enters the small intestine further along than it did before surgery. The liver and pancreas continue to release enzymes which help digest food further down the small intestine.
The stomach pouch created during OAGB is usually slightly larger than the pouch created during a Roux-en-Y gastric bypass.
Expected weight loss
Most people lose weight relatively quickly during the first year following OAGB surgery. You will generally reach your lowest weight around 12–18 months after surgery.
On average, people lose around 60–70% of their excess body weight, equivalent to approximately 25–35% of their total body weight. The amount of weight lost varies between individuals.
Following dietary advice, remaining physically active and making the recommended lifestyle changes can help you achieve and maintain the best possible result.
Advantages
Possible advantages include:
- the amount of food you can eat is reduced
- you are likely to feel full more quickly and stay full for longer
- weight loss tends to be relatively rapid
- average weight loss is greater than with some other procedures
- the procedure usually takes less time than a Roux-en-Y gastric bypass because only one connection, or anastomosis, is made
Disadvantages and possible side effects
These can include:
- lifelong vitamin and mineral supplements
- an increased risk of nutritional deficiencies, including vitamin B12, iron and calcium deficiency
- temporary hair thinning during rapid weight loss
- nausea and vomiting, particularly during the first few days after surgery or if you eat too quickly or too much
- slower weight loss for some people because the stomach pouch is larger than the pouch created during Roux-en-Y gastric bypass
- bile reflux
Bile reflux
Bile reflux happens when bile, a digestive fluid produced by the liver, flows backwards from the small intestine into the stomach pouch and oesophagus. Bile can irritate the lining of the stomach pouch and oesophagus.
The risk of symptoms may be reduced by stopping smoking, eating smaller meals containing less fat and keeping your upper body raised for a few hours after eating.