What are the Medicare eligibility criteria for bariatric surgery in Australia?

Per MBS Online explanatory note TN.8.29, items 31569 to 31581 and anaesthesia item 20791 apply to surgical treatment of clinically severe obesity, generally defined as BMI ≥ 40 kg/m², or BMI ≥ 35 kg/m² with major medical co-morbidities (e.g. diabetes, cardiovascular disease, cancer). MBS notes BMI values may vary across ethnic groups due to differences in body proportions and that some groups may face major health risks below this range. The decision to undertake surgery remains a matter for the surgeon's clinical judgement.

Do bariatric surgery patients need to be on the Bariatric Surgery Registry?

Yes. Per MBS Online note TN.8.29, practitioners providing items 31569, 31572, 31575 and 31581 should be registered with and provide relevant data to the Bariatric Surgery Registry, run from Monash University (School of Public Health and Preventive Medicine).

Does a GP need to refer to a bariatric surgeon via a physician?

No. A GP can refer directly to a bariatric surgeon. A multidisciplinary assessment (surgeon, dietitian, often psychologist) is then arranged through the bariatric service. There is no specialist gatekeeping referral required by Medicare for the surgical items.

What supplements are needed long-term after bariatric surgery?

Lifelong micronutrient supplementation is needed. Typically: a bariatric-specific multivitamin and mineral, vitamin B12, calcium, vitamin D, and iron (especially for menstruating women). Roux-en-Y bypass and biliopancreatic diversion need more aggressive supplementation than sleeve gastrectomy because of greater malabsorption. The exact regimen is set by the bariatric team; annual bloods inform titration.

Bariatric surgery — GP reference

A practical reference for Australian GPs and registrars: the MBS items, the TN.8.29 eligibility definition, who to refer to, and the post-op shared-care routine. Reference only — clinical decisions sit with the bariatric team and the treating GP.

📋 Sources (verified June 2026):

MBS Online — bariatric items 31569 to 31585, 20791, explanatory notes TN.8.29 and TN.8.30 (MBS Book, July 2026).
ANZMOSS — Australian & New Zealand Metabolic and Obesity Surgery Society (position statements, training standards, member directory).
Monash Bariatric Surgery Registry — registry participation required for items 31569, 31572, 31575 and 31581.
Bariatric Surgery Registry — Brown WA et al. ANZ J Surg 2025;95(5):895-903 — real-world AU outcomes.

Reference for registered medical professionals. Not prescribing or referral advice. Confirm fees and item descriptors against current MBS Online before billing.

MBS items at a glance (July 2026)

Item	Procedure	Fee	75% benefit
31569	Adjustable gastric band — placement (with/without crural repair, ≤45 min)	$991.15	$743.40
31572	Gastric bypass — Roux-en-Y (with/without crural repair, ≤45 min)	$1,219.55	$914.70
31575	Sleeve gastrectomy (with/without crural repair, ≤45 min)	$991.15	$743.40
31578	Gastroplasty (excluding gastric plication, with/without crural repair, ≤45 min)	$991.15	$743.40
31581	Biliopancreatic diversion ± duodenal switch (with/without crural repair, ≤45 min)	$1,219.55	$914.70
31584	Surgical reversal / revision / conversion of previous bariatric procedure	$1,795.55	$1,346.70
31585	Removal of adjustable gastric band	$970.70	$728.05
31587	Adjustment of gastric band (independent procedure, incl. associated consult)	$114.30	$85.75
31590	Adjustment / repair / revision / replacement of band reservoir	$293.75	$220.35
20791	Initiation of anaesthesia for bariatric surgery (10 basic units)	$231.00	$173.25

Verify at MBS Online before billing. Bariatric items are not in the auto-updated fees table on this site — confirm current scheduled fees at mbsonline.gov.au. Fees above are the July 2026 schedule and are indexed annually on 1 July.

If crural repair taking ≤45 minutes is done in association with the bariatric procedure, additional hernia repair items cannot be claimed for the same service (per TN.8.29).

Eligibility — what TN.8.29 actually says

Clinically severe obesity per MBS Online (TN.8.29): generally BMI ≥ 40 kg/m², or BMI ≥ 35 kg/m² with major medical co-morbidities (e.g. diabetes, cardiovascular disease, cancer). MBS acknowledges that BMI thresholds may differ across ethnic groups due to body composition differences and that some groups may face major health risks at a BMI below this range. The decision to undertake surgery remains a matter for the surgeon's clinical judgement.

ANZMOSS adds a multidimensional framework using the Edmonton Obesity Staging System (EOSS) alongside BMI — particularly EOSS stages 2+ (established obesity-related chronic disease) and stage 3 (end-organ damage) — to inform prioritisation, especially in the public sector. ANZMOSS positions are not in MBS, but inform multidisciplinary practice.

Bariatric Surgery Registry

Per TN.8.29, practitioners providing items 31569, 31572, 31575 and 31581 should be registered with and provide data to the Bariatric Surgery Registry (Monash University, SPHPM). Audit-grade outcome data on AU/NZ practice — Brown WA et al. ANZ J Surg 2025;95(5):895-903.

Referral pathway from primary care

Direct referral from GP to a bariatric surgeon — no physician gatekeeper required by Medicare.
Most patients are seen in a multidisciplinary clinic — surgeon + bariatric dietitian + (often) psychologist. The team determines suitability and which procedure.
Public access is limited (capacity is a fraction of the eligible population). Most surgery is private; insurance typically requires Gold-tier cover + 12-month waiting period.
ANZMOSS member directory: surgeons, dietitians and psychologists at anzmoss.com.au.

Pre-op — the GP's role

Pre-op investigation, optimisation and counselling checklist

Baseline screening — FBC, EUC, LFTs, fasting lipids, HbA1c, TFTs, iron studies, B12, vitamin D, calcium, magnesium.
Comorbidity workup — OSA screen (STOP-BANG and consider sleep study), CV risk assessment, hypertension review, T2DM optimisation, NAFLD review.
H. pylori testing (especially pre-bypass) — eradicate if positive.
Mental health and substance use review — depression, eating-disorder behaviours, alcohol use, smoking. Smoking cessation before surgery.
Medication review — NSAID avoidance (especially post-RYGB; marginal ulcer risk), diabetes medications (titration as weight falls), oral contraceptive counselling (see below).
VLED briefing — most surgeons require 2–4 weeks of very-low-energy diet pre-op to reduce liver size and operative risk; the dietitian sets the regimen.
Realistic expectations — discuss lifelong supplements, follow-up, and the chronic-disease nature of obesity.

Post-op shared care

Pick the procedure to see the typical supplement and follow-up reference. This is a generic reference — defer to the bariatric team's individual plan.

Pregnancy

Advise avoiding pregnancy for 12–18 months after surgery while weight is rapidly changing and nutritional status is being established. Reliable contraception is needed. Post-RYGB: oral contraceptive absorption may be reduced — advise a non-oral method (IUD, implant, DMPA, vaginal ring, patch) or add a barrier. See UKMEC contraception eligibility. Pregnancies after bariatric surgery are managed by an experienced obstetric team with the bariatric dietitian — nutritional surveillance throughout.

Weight regain and GLP-1 RAs

Some weight regain a few years post-surgery is common. Combination of behavioural review, dietitian input and (in selected cases) GLP-1 receptor agonists may be considered by the bariatric team. See the GLP-1 prescribing guide for access pathway and 2025 TGA safety updates (including the periprocedural and oral contraception advice that are relevant after bariatric surgery too).

Red flags — refer urgently / send to ED

Send urgently: persistent vomiting; severe abdominal pain (especially RYGB — think internal hernia); haemodynamic compromise; sepsis/peritonism; melaena or haematemesis; severe dehydration; suspected anastomotic leak (early) — fever, tachycardia, escalating pain; suspected DVT/PE; severe and new neurological symptoms (consider Wernicke encephalopathy / thiamine deficiency in any post-bariatric patient with vomiting + confusion or ophthalmoplegia — give thiamine, don't wait for confirmation).

Bariatric Surgery — GP MBS Guide