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Bariatric (weight-loss) surgery

Surgical roomWeight-loss surgery is called bariatric surgery. It can be used for people who are very obese and who can't control their weight through any other methods. If obesity is complicated by other medical conditions such as diabetes and heart problems, then losing weight becomes even more important. Surgery may be an option if you have several significant health problems related to your obesity.

The aim of the surgery is to control the amount of food you're able to eat and reduce your excess appetite for food. This limits the calories you're able to consume and allows your body to burn stored energy in the form of fat. This allows you to lose weight.

Types of bariatric surgery

Sleeve gastrectomy

Sleeve gastrectomy involves surgically removing part of your stomach, turning it from a bag into a tube and reducing its volume from 2 litres down to 100 ml. This is a permanent change that can't be reversed. It results in a faster rate of weight loss over nine to 18 months.

Gastric bypass

Gastric bypass involves bypassing much of your stomach and part of your small bowel where absorption of food takes place. It reduces your stomach volume to around 30 ml. This is effective in reducing appetite and results in good weight loss over nine to 18 months.

Gastric band

Gastric band surgery is no longer offered publicly or privately in the South Island. This is because of a high rate of repeat operations needed. The procedure involves placing a silicon band around the top of your stomach, reducing its size. Weight loss is usually slower than with other types of surgery. Also, although reversible, people can develop complications. If you're having difficulty with your gastric band, see your GP to be referred to a surgeon.

Eligibility for publicly funded bariatric surgery

A limited number of people aged between 18 and 60 years are eligible for publicly funded weight loss surgery. Publicly funded means that the public health system pays for the surgery.

Other criteria that you need to meet to qualify for consideration for publicly funded surgery include:

Exclusions to having publicly funded surgery include:

Because there's a limit on the number of publicly funded surgeries available, there's an assessment and selection system in place. The district health boards (DHBs) in the South Island pool their funding for weight-loss surgery. Some patients selected for weight-loss surgery might have to travel elsewhere in the South Island for their surgery.

If you don't want to wait or you can afford to pay for your surgery, you may wish to look at having it done privately.

The assessment and selection process

The following process is the only way to apply for publicly funded weight-loss (bariatric) surgery.

  1. The first step is to see your GP.
    • Your doctor will measure your body mass index (BMI). Only patients with a high BMI (greater than 40) are considered for publicly funded surgery.
    • Your doctor will check if you meet the South Island criteria for bariatric surgery.
    • Before you're considered for surgery, you must have been obese for at least five years. You'll also need to have followed an intensive weight-loss programme for at least two years.
    • Your doctor will ask you about your general health and find out if you have any health problems related to your obesity.
    • Your doctor will assess that you have a clear understanding about the surgery and any potential complications.
    • You may need other checks, including blood and urine tests.
    • If you meet all the qualifying criteria and you want to be considered for surgery, your doctor will explain the process.
  2. Your doctor will then send a referral to the surgical service at your local DHB. They'll include all your relevant medical information in the referral so the surgeon can consider your case.
  3. First, you'll be scored based on the information provided by your GP on the referral form. The triaging doctor will use the National Bariatric Prioritisation Scoring tool to determine your prioritisation score relative to other patients. This scoring system helps decide which patients would most benefit from surgery. As the number of surgeries provided each year is limited, only those patients who achieve a score over the threshold will be offered an appointment with a bariatric surgeon or other health professional.
  4. At this first appointment, the surgeon will confirm your prioritisation score. They'll ask you questions about your health and examine you to help decide if you're a suitable candidate for surgery. The surgeon will explain about the surgery and ask about your understanding of what's involved and your expectations.
  5. If you're still interested in surgery, they'll forward your name for the next step.
  6. Following this first appointment, a committee of experts (South Island Bariatric Surgery Service Multidisciplinary Selection Committee) will review your case. They meet four times through the year to select the most suitable candidates for surgery. It may take up to four months before you find out the outcome.
  7. Throughout this process, the surgeon who assesses you and gives you your ranking will see your medical records. The committee of experts who reviews your case will also see your medical records. Your doctor will make sure you understand this and give your consent to your medical records being used in this way.

If your application is successful

  1. You'll be offered a team assessment appointment with a surgeon, dietitian, psychologist, and exercise specialist.
  2. Your surgery will be arranged with a surgical provider in Christchurch or Invercargill.

If your application isn't successful

Surgical risks

Any surgical procedure has some risks. Your surgeon will talk through possible surgical risks with you and answer your questions.

Along with the more general short-term complications that can occur with any surgery, there are several complications that can occur with bariatric surgery up to several years after having it done. The complications depend on the type of bariatric surgery you have and can include strangulation of the stomach, a leak of stomach contents along a staple line, internal hernias, and vitamin deficiencies. Your surgeon will explain these in more detail if you're having one of these surgeries done.

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Written by HealthInfo clinical advisers. Last reviewed November 2018. Last updated February 2020.

See also:

Overview of surgery

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Review key: HIBAR-51647