Gastric bypass: increased restriction for poor weight loss

Gastric bypass, the most common bariatric procedure performed in the United States, is becoming increasingly popular worldwide. Currently, gastric bypass is most often performed laparoscopically, and anecdotal experience has helped to evolve this operation, minimizing complications and optimizing long-term weight management. With better visualization and video documentation, we can compare outcomes based on anatomic differences between centers. As we debate the nuances concerning the optimal size and configuration of the gastric pouch and the amount of intestine that can or should be bypassed, it is clear that we are only on the verge of understanding the mechanism by which this procedure produces weight loss. Anatomic manipulation is important only if it produces a physiologic response. Whether one subscribes to the theory of a mediated incretin or a purely mechanical mechanism for sustained weight loss, it is agreed that there almost certainly is a metabolic effect associated with the gastric bypass as opposed to the adjustable gastric band or the vertical-banded gastroplasty. Creation of a standard ‘‘gastric reservoir’’ and ‘‘stoma’’ independent of the initial size, energy requirements, gender, or age of the patient is standard for most surgeons. Yet, patients respond with a predictable percentage of excess weight loss. This should be sufficient evidence to refute a purely mechanical mechanism of action for the gastric bypass. In addition, MacLean [3] has shown stoma dilation after gastric bypass to be a consistent finding not necessarily corresponding to inadequate weight loss or weight recidivism. In separate studies, Fobi et al. [2] and Capella and Capella [1] have achieved greater weight loss and maintenance with the banded approach, stabilizing at least one aspect of the anatomy: pouch diameter. Despite long-term data, few surgeons have adopted the banded gastric bypass as a primary operation compared with the majority who have embraced the laparoscopic approach. Debate continues as to the risks and benefits of a reinforced stoma, or more correctly, a stabilized gastric pouch, but most agree that initial, if not, permanent restriction is at least one important aspect of the gastric bypass. More controversial is whether increased restriction is appropriate for patients with inadequate initial weight loss or weight recidivism. Evaluation of patients with inadequate weight loss or recidivism after gastric bypass begins with defining the current anatomy in the context of the potential for optimization. Horizontal pouches will dilate along with the stoma due to the inclusion of the gastric fundus. Surgeons differ concerning the actual size and consistency of the anatomy. Therefore, both upper gastrointestinal and flexible endoscopies are useful and complementary studies. If the current anatomy appears optimal, then other options such as conversion to a duodenal switch or alteration of the intestinal limb lengths should be considered. However, increasing malabsorption with maintenance of restriction may impart a higher risk of protein–calorie malnutrition [4]. Presented at the annual meeting of the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) in Las Vegas, NV, 20 April 2007