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Single Anastomosis Gastric Bypass (mini bypass)

What is the single anastomosis gastric bypass?

The single anastomosis gastric bypass (also known as the mini bypass) has been around since the late 1960s and has recently started to become more popular again. It requires only one bowel join (anastomosis) and is therefore easier to perform than the Roux-en-Y gastric bypass.

Generally, it is completed laparoscopically, meaning the operation is performed via small incisions in the abdomen. The stomach is divided into a small upper portion, leaving the larger, lower portion of the stomach untouched. A loop of bowel is joined to the upper part of the stomach. This allows food to pass straight into the bowel, bypassing the storage capacity of the main stomach. Fats and sugars therefore bypass the stomach, duodenum and upper part of the small bowel where they are normally absorbed, instead passing downstream as waste. Fewer calories absorbed results in weight loss.

Are you eligible for the single anastomosis gastric bypass?

The single anastomosis gastric bypass is available for patients with a BMI of 35 or more, or 30 or more with one or more obesity-related complications.

Advantages of the single anastomosis gastric bypass

  • Similar to operation to traditional Roux-en-Y gastric bypass, but with one less “join” required.
  • Weight loss and health benefits resulting are essentially the same as for standard Roux-en-Y gastric bypass.
  • Reversible procedure as no part of the stomach is moved or removed.
  • Less ulceration.


Lee w-J et al. Laparoscopic Roux-en-Y vs mini-gastric bypass for the treatment of Morbid Obesity: a 10 Year Experience. Obes Surg 2012; 22: 1827-1834.

Find out more

If you’d like to know more about the single anastomosis gastric bypass, make an appointment with one of our experienced surgeons today on (08) 8465 6300.