Tailoring One-Anastomosis Gastric Bypass Based on Total Small Bowel Length - A Randomized Controlled Trial

Scientific Background and Rationale for the Study One-Anastomosis Gastric Bypass (OAGB) is the most common bariatric procedure in Israel [1]. Over the years, OAGB has been proven to be an effective surgery, yielding significant and sustained weight loss, improvement in obesity-related comorbidities, and a relatively low failure rate [2].

The procedure involves separating a long gastric pouch from the remaining stomach and creating an anastomosis between the pouch and a distant loop of the small intestine [3]. Since this procedure bypasses a relatively long intestinal segment (typically 150-200 cm), it results in malabsorption of carbohydrates, fats, proteins, and other nutrients. This malabsorption-related mechanism leads to greater weight loss compared to purely restrictive surgeries like sleeve gastrectomy [4].

The length of the bypassed segment, specifically the biliopancreatic limb (BPL), plays a critical role in determining the metabolic outcomes of OAGB. A longer BPL is associated with more significant weight loss and greater improvement in obesity-related diseases [5]. However, the ideal BPL length remains a topic of global debate. Some experts recommend measuring the total small bowel length (TSBL) or ensuring at least 250-300 cm of common channel (CC) to prevent pathological malabsorption in patients with a shorter bowel and to reduce the risk of weight regain in those with a longer bowel [3,6].

Currently, the most widely accepted approach is to standardize the BPL length at 150-200 cm, as studies have shown that this range minimizes the risk of nutritional deficiencies [7]. However, tailoring the BPL length to the patient's TSBL is an increasingly recognized strategy that may optimize outcomes by ensuring a more precise CC length, thereby reducing complications and improving long-term weight loss.

Study Objective To evaluate whether tailoring the BPL length to the TSBL results in more effective weight loss compared to a standard bypass length of 180 cm.