Gastric bypass, as the name denotes, is the ‘by-passing’ (hiding) of food, from the stomach and upper part of the small intestine. In the “classic” or RNY gastric bypass, a small pouch of stomach is fashioned, which is then connected to a specially constructed (Roux limb) channel of intestine that joins with the regular course of intestine, at a Y-shaped junction. Hence called, as the Roux-en-Y gastric bypass.
This procedure has been widely used in USA with the longest follow up results. Many consider this as a ‘gold-standard’ operation. However, as this has two areas of division and re-connection (anastomosis) it increases the chances of complications, like narrowing and intestinal obstruction, which can result in vomiting and abdominal pain. Moreover, due to the re-routing of the intestine there is a risk of nutritional deficiencies. The nutritional risk (and the weight loss) is directly proportional to the length of intestine that is by passed. The longer bypass has greater nutritional deficiencies and the shorter ones have lesser nutritional deficiencies.
However, in the recent years, there has been a fall in the number of this classic bypass operations, in favor of the sleeve gastrectomy. In the latter, there is no re-routing of food, or intestinal re-connections (anastomoses) hence, sleeve gastrectomy is a much simpler operation with relatively, lesser risk of nutritional deficiencies and complications. However, studies show that gastric by-pass has better results in resolving Type 2 diabetes than sleeve gastrectomy, because of excluding the upper small intestine. The classic bypass may also give equal weight loss effects, if not better, compared to the sleeve gastrectomy.