Although meat and vegetables fill the gastric pouch quickly and empty slowly, patients soon learn that they can eat greater volumes by taking highly refined foods which empty more promptly. Although gastric bypass is associated with greater weight loss than is achieved with gastroplasty, it is technically demanding and may be associated with higher rates of morbidity. Exclusion of a sufficient volume of the parietal cell mass suppresses antral gastrin secretion and stomal ulceration. The size of the stoma in gastric bypass procedures is not as critical as in gastroplasties and patients may be able to eat a greater variety of foods. The use of large stapling devices in the upper abdomen in a grossly obese patient is not easy and the addition of a hand-sutured anastomosis to the stapled gastric fundus compounds the problem.
More complex operations result in a higher complication rate.
Many skilled surgeons have encountered problems in the subdiaphragmatic area even in patients who are not fat. The major concern with gastric bypass is anastomotic leakage, which may occur in 5 per cent, even in skilled hands. Despite the small parietal cell mass, stomal ulceration is also a problem. If H2-receptor or proton pump antagonists fail, revision procedures, with reduction of the volume of the pouch and truncal vagotomy, may be required. Excessively high serum gastrin levels may require resection of the excluded stomach.