One-Anastomosis Gastric Bypass

Who is it for?

One-anastomosis gastric bypass may be right for you if you are an adult and one of the following applies:

• Your body mass index (BMI) is 35 or more, with or without health problems linked to your weight.
• Your BMI is between 30 and 35, and you have a health problem linked to your weight, such as type 2 diabetes, high blood pressure, sleep apnea (pauses in breathing during sleep), wear and tear of the joints (osteoarthritis), high cholesterol, or fatty liver.
• Your BMI is between 30 and 35, and other treatments have not kept the weight off.

It works especially well for people with a high BMI or type 2 diabetes, and it can be used as a second operation after a sleeve in selected patients. If you already have strong acid reflux, a classic Roux-en-Y bypass is usually a better choice.

How is it performed?

• You are fully asleep under general anesthesia. The operation is done by keyhole surgery through 5 small cuts and takes about 45 to 60 minutes.
• A long, narrow tube is made from the upper part of the stomach.
• This tube is joined to a loop of the small intestine about 150 to 200 cm from its start, depending on your BMI. This single join is where the name “one-anastomosis” comes from.
• Food passes from the stomach tube straight into the lower intestine, skipping the first part. Digestive juices still meet the food further along.
• The rest of the stomach is not removed. It stays inside and keeps making digestive juices.
• The join is tested for leaks before the operation ends.

Before surgery

• A full check-up: blood tests, an abdominal ultrasound, an upper endoscopy (a camera test of the stomach), and a visit with the anesthesia doctor.
• A session with our dietitian. If your BMI is very high (over 60), you will also follow a low-calorie diet for 1 to 2 weeks before surgery, to shrink the liver and make the operation safer.
• Stop smoking at least 4 to 6 weeks before surgery, and do not start again. Smoking can cause a stomal ulcer where the stomach tube meets the intestine.
• Tell us about all your medicines, especially for diabetes, blood pressure, and blood thinning.
• Our Fast Track program starts now and continues during and after your operation, to help you recover sooner.

Recovery and follow-up

• You will walk within a few hours and start sipping water on the first day. Most patients go home after one night.
• Your diet moves in steps over about six weeks: clear fluids, full fluids, puréed food, soft food, and then healthy normal meals in small portions. Eat enough protein at every meal.
• You will take vitamins every day for life: a multivitamin, vitamin B12, iron, calcium, and vitamin D. Blood tests at 3, 6, and 12 months, then once a year, keep your levels healthy. For the first 6 months, you will also take a medicine that protects you from gallstones.
• Avoid anti-inflammatory painkillers such as ibuprofen, diclofenac, and aspirin unless your doctor prescribes them. Paracetamol is usually safe.
• Follow-up visits are at 1 week, 1 month, 3, 6, and 12 months, then twice a year, in the clinic or by video consultation.

What results can I expect?

Most patients lose about 70–90% of their extra weight over the first 12 to 18 months. Type 2 diabetes often improves quickly, and many patients reduce or stop their medicines. As with every weight-loss operation, lasting results depend on your eating habits, activity, and follow-up.

Conditions That May Improve

1. Severe obesity
2. Type 2 diabetes

What are the risks?

Every operation carries some risk, and we will explain yours at your consultation. The main risks are:

• A leak. This is very rare today, thanks to advanced staplers and the surgeon’s experience. If it happens, it shows within the first 7 to 10 days after surgery.
• Bleeding, in about 1 in 100 patients. It usually settles with close monitoring and treatment, without another operation.
• Bile reflux: bile flowing back up into the stomach tube, causing burning or a bitter taste. It affects a small number of patients and is treated with medicine or, if it persists, by changing to a Roux-en-Y bypass.
• A stomal ulcer: a small sore where the stomach tube meets the intestine. It is more likely if you smoke or take anti-inflammatory painkillers.
• Shortages of iron, vitamin B12, vitamin D, calcium, or protein if supplements and follow-up are missed.
• Looser or more frequent bowel movements in some patients.
• Gallstones. Fast weight loss and drinking too little water can cause them, and without prevention, about 25–30% of patients develop them. A protective medicine we prescribe for the first 6 months lowers this to about 5%, close to the usual rate in the general population.
• Blood clots in the legs or lungs. Walking early and blood-thinning injections lower this risk.
• Some weight regain over the years. Regular follow-up with our nutrition team is the best way to prevent it.

Why Choose Our One-Anastomosis Gastric Bypass Program?

• Experienced bariatric surgeons
• Advanced laparoscopic technique
• Careful assessment of reflux before surgery
• Personalized choice between OAGB, sleeve gastrectomy and gastric bypass
• Nutritional preparation and vitamin follow-up
• Long-term follow-up programme