Gastric tube volume after duodenal switch and its correlation to short-term weight loss

Background: Bariatric operations may have a restrictive and a malabsorptive component. The restrictive component is considered key for short-term weight loss. However, there are important volume discrepancies between gastric reservoirs in different bariatric surgical techniques, which questions the real meaning of the restrictive part of the operation. We have investigated the relationship between residual gastric volume after sleeve gastrectomy in duodenal switch (DS) and weight loss over the first postoperative year. Methods: 14 patients submitted to a modified DS and one patient submitted to a sleeve gastrectomy were studied. All patients had an abdominal CT performed between the third and the ninth postoperative month to measure residual gastric volume. Gastric tube volume was correlated to early postoperative weight loss. Results: Mean excess BMI loss was 75% at 12 months. Mean gastric tube volume was 208 cc. Gastric volume was not related to preoperative weight or BMI; instead, it was directly related to patient’s height. There was no statistical relation between gastric volume and weight loss at 3, 6, 9 or 12 months after the operation. Conclusion: After DS, gastric tube volume is not directly related to weight changes. Other factors could have influence on intake restriction, such as gastric tube compliance or different mechanisms of satiety induction, because no differences in weight loss were observed between narrow tubes and wider ones, despite important variations in volume.