The one anastomosis bypass is performed laparoscopically, or keyhole, through 5 small cuts to your abdomen.

The surgical procedure involves using a bougie, or plastic tube, inserted through the mouth to guide the creation of a small stomach pouch. This pouch is then joined to the bowel, 150cms from the start of the duodenal-jejunal (DJ) flexure (a part of the small bowel).

The surgeons at Morphē perform one anastomosis as a primary surgery for someone who has not had other weight loss surgeries previously, or as a revision operation for someone who has had weight loss surgery previously.

Guidelines for eligibility include:

• Age >18
• BMI 30 with weight related comorbidities
• Or BMI ≥ 35 with no comorbidities needed
• No eating disorders
• No untreated acute psychiatric disorders
• No alcohol or drug dependency
• Has tried other avenues without success
• Committed to a healthy lifestyle and lifelong care

Note: these are guidelines, and all patients require a discussion regarding one anastomosis gastric bypass and other forms of bariatric surgery.

Patients can expect to lose around 65-75% of excess weight, or 30-35% of total body weight, with the majority occurring in the first year.

For example, a 176cm patient who weighs 140 kgs, has a BMI of 45. Their ideal weight is 78 kgs (for a BMI 25), which means an excess weight of 62 kgs.

This means that this patient can expect to lose around 43 kgs and end up at around 97 kgs as a rough guide.

A possible serious risk of one anastomosis surgery is a leak, which is very rare at <1% with high-volume Australia surgeons, but may need a further operation to manage.

Another risk is an ulcer at the join between the stomach and bowel (anastomosis). This ulcer is more likely to occur in patients who take up smoking again or use anti-inflammatories.

Anti-inflammatories, such as Nurofen, Mobic, Voltaren, or prescription anti-inflammatories increase the risk of ulceration significantly and cannot be taken at all with a bypass, including from 6 weeks prior to the operation. An ulcer can cause pain, can bleed and even perforate.

Smoking is another risk factor for ulcers and cannot be undertaken at all following a gastric bypass.

Another issue associated with the one anastomosis gastric bypass is bile reflux. This may result in an unpleasant taste in the patient’s mouth, and acid reducing medication does not improve these symptoms. An endoscopic outlet reduction (Overstitch) or Roux-en-Y bypass may be required in around 1-2% of patients to resolve bile reflux.

Your surgeon will discuss all risks and possible side effects with you.