Mini Gastric Bypass

The mini gastric bypass (MGB) is a variation on the classically described Roux-en-Y gastric bypass (RNYGB). It is also known as the one anastomosis gastric bypass (OAGB); single loop gastric bypass or less commonly the omega loop gastric bypass.

The mini gastric bypass was first described over 20 years ago. The procedure has undergone some changes and improvements in the following years. The current procedure has a component of restriction by creating a long narrow gastric pouch (a very small stomach). Even more significant than restriction (and by far the single most important factor) is the metabolic effect. These changes occur as a consequence of bypassing between 150 and 200 cm of small intestine. This is what really drives the weight loss and typically, results. These arise from the loss of appetite and early satiety (feeling full). That is not to say that patients no longer enjoy food – on the contrary. Patients do enjoy food, but they eat a much smaller portion to achieve the same feelings of fullness than prior to surgery.

Much like any of the other metabolic procedures including the RNYGB and gastric sleeve (LSG) there is an improvement in patients’ obesity related diseases. Diabetes, high blood pressure, sleep apnoea amongst a myriad of other diseases usually improve markedly. Frequently they resolve altogether. It is interesting to note that diabetes typically improves immediately after surgery. This is even before any significant weight loss. That’s because of the powerful metabolic effect of the surgery.

“MGB and OAGB have become internationally accepted bariatric and metabolic operations – the fastest growing procedures, now in 3rd place among surgical options against severe obesity and associated diseases.” Dr Arun Prasad MGB-OAGB-Club-President 2020

How does the mini gastric bypass work?

The MGB results in weight loss for several reasons. The first is the powerful metabolic effects of the surgery. By dividing the stomach into a small pouch and a larger remnant stomach, we disrupt the normal chemical signals (hormones). This results in decreased hunger and earlier feelings of fullness. This is further improved by bypassing the small intestine. Doing this increases the changes in chemical signals going from the gut to the brain and back the other way.

The creation of a small gastric pouch also restricts volume. In simple terms, this means the patient’s stomach can physically fit much smaller amount of food and liquid than the normal stomach is able to.

How can I make the most of surgery?

How do you get the most out of the MGB? Participating in both follow up care and implementing lifestyle changes are crucial. This means following the advice of your surgeon. As well as your bariatric physician, dietitian, psychologist and exercise physiologist.

Paying particular attention to the following key areas is crucial:

  • Diet. A healthy diet is so important. This might look like a protein based diet, with some healthy fats and fewer carbohydrates. Your dietitian will determine your individual needs.
  • Water. You will need to be consistent with water intake. Regular water intake is necessary to ensure hydration.
  • Fibre. Extra fibre is also an important consideration, and we recommend psyllium derivatives.
  • Vitamins. You will need to take daily multivitamins to ensure optimal nutrition.
  • Load bearing exercise. Apart from general physical activity, commit to load bearing exercise. This might look like lifting weights, using resistance bands or using body weight. We usually recommend 30 minutes of load bearing exercise 3-4 times each week.
  • Mindset change. Minding your mind is beneficial. I cannot overemphasise its benefits for the bariatric patient. I can recommend a psychologist, mentor or coach (or all three). As well, personal development info and books can change your outlook.
  • Support crew. While not crucial, many patients find gathering a crew of supportive friends helpful. Apart from the professionals, you might find a buddy, a support group, or even a Facebook group. A good crew can help you maintain a positive outlook (and stay on track).
  • Consistency is key. Show up every day and commit to the lifestyle changes you need to make. I am all about fostering great habits in the early days post-surgery, to set you up for long term success.

Can you explain the procedure?

We typically perform the surgery laparoscopically (keyhole surgery) as described in the following steps-

  1. The surgeon makes 5 very small (5-12mm) cuts to introduce ports into the abdominal cavity which they inflate with gas. Then they pass a camera and working tools through these ports to perform the surgery.
  2. The surgery involves creating a small gastric pouch (the new stomach) using a special stapler. The larger (remnant) stomach remains where it is.
  3. The next step is measuring 150-200 cm of small bowel from the start of the small intestine and then joining this to the gastric pouch (anastomosis).
  4. Once complete, the surgeon removes the ports, releases the gas and closes the incisions.
  5. As shown in the diagram, the digestive juices pass from the stomach and into the upper part of the small bowel (the bypassed portion). After the bypassed portion reaches the join with the gastric pouch, it mixes with food and liquid which has entered the gastric pouch from the oesophagus. Only then digestion and absorption of nutrients occurs.
  1. The surgeon makes 5 very small (5-12mm) cuts to introduce ports into the abdominal cavity which they inflate with gas. Then they pass a camera and working tools through these ports to perform the surgery.
  2. The surgery involves creating a small gastric pouch (the new stomach) using a special stapler. The larger (remnant) stomach remains where it is.
  3. The next step is measuring 150-200 cm of small bowel from the start of the small intestine and then joining this to the gastric pouch (anastomosis).
  4. Once complete, the surgeon removes the ports, releases the gas and closes the incisions.
  5. As shown in the diagram, the digestive juices pass from the stomach and into the upper part of the small bowel (the bypassed portion). After the bypassed portion reaches the join with the gastric pouch, it mixes with food and liquid which has entered the gastric pouch from the oesophagus. Only then digestion and absorption of nutrients occurs.

“MGB/OAGB procedure is an established procedure, not only are the numbers of procedures increasing, but so are the number of research papers, which increased by 31% in 2018,” concluded professor Almino Ramos (President IFSO).

Are there risks with the MGB surgery?

All surgery, no matter how minor or how major, has risks. Your surgeon will explain these risks in detail to you. You should make sure you understand these risks clearly. This is required for you to make ‘informed consent’ for the procedure.

We always balance the risks against the benefits of surgery (risk-benefit analysis). Weight loss surgery has been shown to be effective and, more importantly, safe. The major risk profile is comparable to commonly performed procedures including laparoscopic cholecystectomy (gallbladder removal), hysterectomy (removing the uterus) and hip arthroplasty (joint replacement).

The mini gastric bypass has a number of risks. These can include a leak (staple line or suture breakdown), bleeding, ulcers, stricture (narrowing of a gut join), or internal hernia. There may also be risks associated with the anaesthetic itself.

The MGB has a slightly higher risk of nutritional deficiencies compared to the RNYGB. You can reduce this risk by taking your multivitamins daily and getting regular (6 monthly) blood tests.

You will receive from your surgeon, in addition to their explanation, an information leaflet from the Royal Australasian College of Surgeons (RACS). This further explains in lay terms the nature of the surgery and the risks involved.

Am I a candidate for MGB?

Are you wondering if you qualify for mini gastric bypass?  Surgery is a big decision, and you may want as much information as possible to understand if it’s right for you. Why not meet me in person, either at one of my information evenings, or by booking an appointment through our clinic. I can answer any questions you might have too.

Find out more about how to book an appointment.