The mini gastric bypass, properly called one anastomosis gastric bypass (OAGB), is a keyhole weight loss operation. The surgeon staples the stomach into a long narrow tube and joins it to a loop of small intestine about 150 to 200 cm downstream, so food skips the rest of the stomach and the first part of the bowel.
It produces weight loss and diabetes improvement comparable to, and in some studies slightly greater than, the classic Roux-en-Y bypass, with a shorter operation and only one join. The trade-offs are a risk of bile reflux into the stomach pouch and a higher chance of vitamin, iron and protein deficiency, so lifelong supplements and blood tests are not optional.
What Mini Gastric Bypass (One Anastomosis Gastric Bypass) involves
Work-up includes blood tests, endoscopy to check for reflux, hiatus hernia and Helicobacter, abdominal ultrasound, heart and lung assessment, and dietitian and psychological review. A liver-shrinking diet for 1 to 2 weeks is usual. Under general anaesthetic, through 4 to 5 small incisions, the surgeon divides the stomach with staplers starting low on the lesser curve and running up to the angle near the oesophagus, creating a pouch around 15 to 18 cm long. The small bowel is measured from its start and a loop is brought up and joined side to side to the bottom of the pouch. The join is tested for leaks with dye or air. The rest of the stomach stays in place and continues to make digestive juices.
Who is a good candidate for Mini Gastric Bypass (One Anastomosis Gastric Bypass)?
Eligibility follows international bariatric criteria, and the choice between operations depends on your reflux, diabetes and eating pattern.
- BMI of 40 or more, or 35 or more with conditions such as type 2 diabetes, hypertension or sleep apnoea
- BMI 30 to 35 with poorly controlled type 2 diabetes, in selected cases
- Revision after a failed gastric band or sleeve with weight regain
- People who will reliably take supplements and attend blood tests for life
It is usually not the right choice if:
- Significant acid or bile reflux, Barrett's oesophagus or a large hiatus hernia, where Roux-en-Y bypass is preferred
- Inflammatory bowel disease affecting the small bowel
- Active alcohol or drug dependence, or untreated eating disorders
- Anyone unlikely to manage lifelong supplementation and follow-up
- Pregnancy planned within the next 12 to 18 months
Technique options
- Standard OAGB with 150 cm limb: The usual configuration, balancing weight loss against nutritional risk.
- Longer biliopancreatic limb (180 to 200 cm): Considered for very high BMI; stronger effect, more deficiency and diarrhoea.
- Tailored limb after measuring total bowel length: Some surgeons measure the entire small bowel so that enough absorbing length remains.
- Conversion from sleeve gastrectomy: Used for weight regain after sleeve, provided reflux is not the main complaint.
What happens during your treatment
The operation lasts 60 to 90 minutes under general anaesthetic. You are walking the same evening to lower clot risk. Expect shoulder-tip and wind pain for a day or two from the gas used. Hospital stay is 2 to 3 nights, with a leak test or clinical checks before discharge.
Preparing for your trip
Plan for 6 to 8 days in Istanbul. Your surgeon reviews photographs and your medical history before you book, and you meet in person the day before surgery for examination, marking and consent with a professional interpreter.
- Stop smoking and nicotine at least four weeks before and after surgery; it is the single biggest avoidable cause of wound problems
- Tell the team about every medicine and supplement you take; blood thinners, some herbal products and hormone treatment may need to be paused on your doctor's advice
- Arrange for someone to travel with you or to be reachable, and keep the first days at home free of work and lifting
- Book a changeable return flight; your surgeon confirms when you are fit to fly
Recovery and results
Diet advances from liquids (2 weeks) to purees (2 weeks) to soft food and then normal textures by about 6 to 8 weeks. Desk work is realistic at 2 weeks. Blood thinning injections continue for 2 to 4 weeks. Most weight is lost in the first 12 to 18 months, typically 60 to 80 percent of excess weight. You need a daily multivitamin, iron, calcium with vitamin D, vitamin B12 and often fat-soluble vitamins, with blood tests at 3, 6 and 12 months and then yearly.
- Back to everyday activity: 2 weeks
- When results show: Most weight loss in 12 to 18 months
- How long they last: Long term with lifelong supplements and follow-up
Safety, risks and revision policy
Serious complications are uncommon in experienced units but can be life-threatening. Some late problems are specific to this design.
- Leak from the staple line or the join, in about 1 percent, needing urgent treatment
- Bleeding, blood clots in the legs or lungs
- Bile reflux with burning, vomiting of bile or inflammation of the pouch, sometimes requiring conversion to Roux-en-Y
- Marginal ulcer at the join, strongly linked to smoking and anti-inflammatory painkillers
- Iron deficiency anaemia, low B12, vitamin D, and in a few people protein malnutrition or persistent diarrhoea
- Dumping syndrome and low blood sugar after sugary food
- Gallstones during rapid weight loss
- Weight regain over the years
Every written proposal arranged through Clinic-Y states what the clinic covers if a correction is needed. Ask for it before you book, not after.
Cost of Mini Gastric Bypass (One Anastomosis Gastric Bypass) in Türkiye
Clinic-Y does not publish a single price for Mini Gastric Bypass (One Anastomosis Gastric Bypass), because the honest figure depends on your case. What moves it:
- Primary surgery versus revision of an earlier operation
- Staplers and energy devices used
- Hospital nights and intensive care availability
- Pre-operative tests including endoscopy
- Aftercare package: dietitian access, blood tests and supplements
Send your photographs or reports and you receive written, all-inclusive proposals from suitable teams, side by side. Reviewing your case is free.
Frequently Asked Questions
How is it different from a standard gastric bypass?
There is one join instead of two and a longer stomach pouch. Surgery is quicker. The downside is that bile can reach the pouch, and deficiencies are somewhat more frequent.
Is it reversible?
It can be reversed or converted more easily than most bariatric operations, though any revision carries added risk.
Who will follow me up at home?
Arrange this before surgery. You need a GP or bariatric service willing to run annual bloods for iron, B12, folate, vitamin D, calcium, PTH and albumin.
Can I take ibuprofen afterwards?
Avoid anti-inflammatory painkillers and smoking for life, as both markedly raise the risk of ulcers at the join.