Gastric Bypass

In a gastric bypass, a small pouch is made at the top of the stomach and joined to the small bowel, so food bypasses most of the stomach and the first part of the bowel. Dr Lourensz performs both the Roux-en-Y gastric bypass and the one anastomosis gastric bypass.

All Weight Loss Surgery options

Types of Bypass

  • Roux-en-Y gastric bypass (RYGB): the pouch is joined to a loop of bowel that has been divided and rejoined in a Y shape. It can help control acid reflux and diverts bile away from the stomach pouch. It is often favoured when significant reflux is present. There are two joins in this operation.
  • One anastomosis gastric bypass (OAGB): the pouch is joined to a single loop of bowel, so there is only one join. OAGB can cause bile reflux, so symptoms and investigations such as gastroscopy help guide careful selection. How much bowel is bypassed matters, and this was part of Dr Lourensz's PhD research.

Who It Suits

For people living with obesity, a bypass should be considered if you also have significant reflux or a hiatus hernia, or need revision after a lap band or sleeve. Dr Lourensz will help you decide which type suits you best.

Things to Consider

  • A different risk profile. A gastric bypass (Roux-en-Y or OAGB) has a different risk profile to a gastric sleeve, in both the short and long term.
  • Supplements for life. A bypass reduces the absorption of some vitamins and minerals, so lifelong supplements and regular blood tests are essential.
  • Smoking and anti-inflammatory tablets (such as ibuprofen) increase the risk of ulcers at the join (marginal ulcers). These can cause pain or serious problems, including a hole in the join, even many years after surgery. If you smoke, a gastric bypass is almost never appropriate.
  • Dumping. Sugary or fatty foods can cause nausea, sweating, cramps or diarrhoea.
  • Long-term follow-up is important so that any problems are picked up early.
  • Internal hernia. Bowel can slip through a gap created by the rerouting and become twisted or blocked, even years later. Severe abdominal pain after a bypass needs urgent assessment, and sometimes a further operation.

Pregnancy and Contraception

Pregnancy is not recommended for 1 to 2 years after weight loss surgery. Discuss pregnancy plans and reliable contraception before surgery.

After either type of gastric bypass, the oral contraceptive pill may be absorbed unreliably, which may affect its efficacy. Non-oral methods of contraception are recommended. Discuss a suitable method with your GP or treating clinician.

The Operation and Recovery

The operation is done by keyhole (laparoscopic) surgery. Most people stay in hospital for one to two nights. You then follow a staged diet over several weeks, with support from Dietitian Louise Becroft.

Risks

Risks include a leak, bleeding, blood clots, ulcers at the join, internal hernia (bowel slipping through a gap created by the rerouting, which can occur years later), dumping, nutritional deficiencies and the need for further surgery. Dr Lourensz will go through your own risks in detail and answer your questions.

Next Steps

Read about the Weight Loss Program, or ask your GP for a referral and request an appointment.

Reviewed by Dr Kaleb Lourensz