Single Anastomosis Gastric Bypass is an advanced bariatric surgery designed to achieve powerful, long-term weight loss by combining stomach reduction with intestinal bypass.
Single Anastomosis Gastric Bypass (also known as OAGB or Mini Bypass) is a modern variation of the traditional Roux-en-Y Gastric Bypass (RYGB). Unlike the RYGB, this operation requires only one bowel join (anastomosis), reducing operative risk while still offering powerful metabolic and weight-loss effects.
Although it carries more surgical risk than sleeve gastrectomy, it generally has fewer long-term complications than RYGB and avoids issues such as internal herniation. This procedure often results in 75–85% excess weight loss, making it one of the most effective bariatric options available.
The operation is performed laparoscopically under general anaesthesia. Five small incisions are made, and the surgeon begins by dividing the lesser omentum to expose the stomach. A small, narrow gastric pouch is then created using a stapling device and calibrated for accuracy. The remaining stomach stays in the body but is disconnected from the food pathway.
At Circle of Care, we add extra reinforcement by burying the top portion of the staple line to reduce the risk of leaks and applying additional sutures for safety.
Next, 200 cm of small intestine is measured and bypassed. The intestine is then brought up and joined to the new stomach pouch using both staples and a double layer of sutures to ensure a secure connection. This creates a new digestive pathway where food moves from the oesophagus into the pouch and directly into the intestine, limiting calorie absorption.
The procedure concludes with dissolvable sutures at each port site, local anaesthetic for comfort.
The surgery promotes weight loss by significantly reducing appetite and meal size while also limiting calorie absorption. With a smaller stomach pouch, patients naturally feel satisfied with much smaller portions.
Because 200 cm of small intestine is bypassed, fewer calories and nutrients are absorbed, leading to 75–85% excess weight loss over 12–18 months, with some patients achieving full excess weight loss. This procedure also triggers major metabolic improvements, particularly in diabetes and obesity-related conditions.
Due to reduced nutrient absorption, patients require lifelong follow-up. Blood tests every six months help monitor Vitamin D, Calcium, B12 and Iron to prevent issues such as anaemia, osteoporosis or nerve symptoms. Our Allied Health team supports patients with eating techniques, supplement routines and lifestyle guidance to ensure long-term success.
This procedure reduces the size of the stomach and reroutes a portion of the small intestine, limiting food intake and nutrient absorption. This leads to significant weight loss, typically 75–85% of excess weight over 12–18 months, while also reducing appetite and changing hunger-related hormones.
Most patients stay in hospital for a few nights and can gradually return to light activities within 2–3 weeks. Long-term follow-up includes dietary guidance, lifestyle support, and regular blood tests to monitor for nutrient deficiencies, ensuring safe and effective weight loss.
