Mini Gastric Bypass

(Single Loop Gastric Bypass)

A gastric bypass is a surgical procedure to treat obesity that involves reducing the size of your stomach to facilitate early satiety and bypassing a section of your intestine to limit food absorption. As with the sleeve procedure, a reduction in size of the stomach restricts the amount of food intake and appetite.

BWLS mini gastric bypass

Procedure Mini gastric bypass, One anastomosis gastric bypass

This procedure was traditionally carried out by a Roux-Y procedure where stomach and intestine are reconnected in two places. A single anastomosis gastric bypass is a modification that simplifies this procedure, reducing operating time and complications both early and late.

EXPECTED WEIGHT LOSS: 30-50% total body weight loss


Laparoscopic, 5 small incisions
Less than one hour

The gastric pouch is constructed similar to a sleeve gastrectomy but not as long. The small bowel is then measured 150-200cm downstream and joined to the end of the gastric pouch.




  • Laparoscopic procedure “keyhole surgery” so less invasive
  • Limits the amount of food ingested and also the calories absorbed
  • Increases intestinal production of GLP1 which stimulates insulin release and is more potent for diabetes cure
  • Ability to eat bread and meat is a little easier
  • A little more weight loss than sleeve
  • Potentially reversible


  • Vitamin and trace element deficiency
  • Intolerance to certain foods
  • Dumping syndrome
  • Requires a lifelong multivitamin
  • Bile reflux, though rare


  • High BMI >45
  • Diabetics
  • Severe reflux
  • Prior gastric banding
  • Patient preference


After gastric bypass surgery:

  • you will stay in hospital for 1 night and have an x-ray in the morning (gastrograffin meal)
  • you will have pain relieving medications to keep you comfortable
  • you will be given instructions to follow regarding wound care, diet and activity
  • you will take Somac or Nexium for 3 months and then stop if reflux free

Patients should:

  • Keep the incision area clean and dry
  • Avoid strenuous exercises and lifting heavy weights for 2 weeks
  • Sip water throughout the day to prevent dehydration
  • Follow the diet regimen given to you by the dietitian
  • Follow a weight loss exercise program to maintain weight loss


  • Lifelong follow up with a physician is required for blood tests to ensure proper health and nutrition
  • Bowel leak through the anastomosis (surgical joins)
  • Gallstones
  • Dumping syndrome – meals flood the intestine causing dizziness, nausea and diarrhoea
  • Nausea
  • Dehydration
  • Indigestion
  • Reactive hypoglycaemia
  • Nutrient deficiencies
  • Incisional hernia
  • Wound infections
  • Marginal ulcers
  • Stomal stenosis
  • Haemorrhage
  • Infection
  • Bleeding
  • Bile reflux
  • Venous thromboembolism

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