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Mini-Gastric Bypass, less complications and less weight regain in the long term compared to standard gastric bypass.

March 25, 2017

The mini-gastric bypass, or single anastomosis gastric bypass, is an effective and well-established procedure which combines some of the properties of a gastric sleeve and a standard gastric bypass. The upper part of the stomach is divided into a tube, similar to the top three quarters of a sleeve, and then joined to a loop of intestine.

The mini-gastric bypass can be used as a primary weight loss procedure. It can also be used in patients who have had previous gastric banding or sleeve surgery but have been unsuccessful with weight loss, or who have had band-related complications and have decided on revision surgery.

It is not ideally suited to patients with symptoms of reflux disease (severe heartburn that needs medication).

How does the mini-gastric bypass help you to lose weight?

The mini-gastric bypass procedure helps you to lose weight in different ways:

1. By reducing the feeling of hunger through altered gut to brain signalling

2. By enabling an earlier feeling of satiety and fullness when eating a meal resulting in a healthy portion size

3. By decreasing the amount of calories you absorb from your food as a result of bypassing 150 to 200cm of the upper part of the small intestine

4. Rerouting of the food stream produces changes in gut hormones that reverse one of the primary mechanisms by which obesity-induced type 2 diabetes occurs

It is an operation that provides good weight loss with great quality of life. The long-term results of the surgery – weight loss, effect on accompanying diseases, low mortality rate – are well documented and reliable.

Mini-Gastric Bypass

Mini-Gastric Bypass

The mini-gastric bypass procedure is performed laparoscopically (keyhole surgery) under general anaesthesia. Five small incisions (between 5 and 12mm in length) are made for the insertion of the keyhole surgery instruments. Using these instruments, the top of the stomach is stapled to form a thin tube (30ml to 50ml in size). The thin tube becomes the new, smaller stomach and is completely separate to the rest of the stomach. This stomach is then sewn to a loop of the small intestine, bypassing the first part of the intestine called the duodenum and approximately 150–200cm of the bowel. The rest of the stomach and upper part of the small intestine remains in the body but is no longer used for food digestion. In skilled hands, the surgery takes approximately 60 minutes to perform.

What are the long-term effects of the mini-gastric bypass?

Long-term effects of any weight loss surgery are reliant on a patient making the necessary changes to lifestyle, particularly in relation to diet and exercise.

Several studies have been carried out and published on the long term (over 5 years) effects of mini-gastric bypass surgery. Two years after the surgery, weight loss is 75-85% of excess body weight; five years after the surgery, the excess body weight loss is 70-75%.

Weight loss with mini-gastric bypass is as good, if not better, than that achieved with standard gastric bypass surgery in people with a higher BMI.

Many diseases connected to being overweight like sleep apnoea, type 2 diabetes, joint diseases, high blood pressure or polycystic ovary syndrome (PCOS) improve or disappear as a result of the surgery.


Mini-gastric bypass is particularly effective for patients with a higher BMI as the procedure has more predictable and durable weight loss outcomes compared with standard gastric bypass.

Most patients have an almost immediate reduction in their need for diabetic medication and some are able to completely stop diabetic medication altogether.

It does not require any on-going adjustments which are required with other procedures, such as the gastric band. Regular follow-up is, however, necessary to ensure weight loss is appropriate and food intake is nutritionally adequate.

It is effective for those people who tend towards high sugar or high fat foods. Dumping syndrome is directly linked to a high sugar, high fat intake. Symptoms of dumping are unpleasant and therefore discourage the intake of high calorie and sweet foods.


Lifelong usage of food supplements and vitamins is necessary for all patients.

Risk of severe malnutrition requiring reoperation in 0.5-1% of patients.

Risk of anaemia (low haemoglobin), caused by low iron levels.  Women of child-bearing age are most at risk.

Contrary to common concern, no studies have shown that mini-gastric bypass increases the likelihood of severe reflux or gastroesophageal cancer.


As with any surgical procedure, the mini-gastric bypass operation has a risk profile which is important to understand before proceeding. The following is a comprehensive list of issues which can occur. Most of these complications are very rare and 90–95% of patients have no issues. This list is extensive and is not intended to worry you, but simply inform you about the range of possible complications, regardless of how rare the issue may be.

In summary, mini-gastric bypass is suitable for almost all patients; it results in remarkable and sustainable weight loss and good control of accompanying diseases, improved quality of life and increased life expectancy.

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