There are several complications that can occur with weight loss surgery. The typical complications for any type of operation are bleeding, infection, injury to other organs, and the risks of general anesthesia. The sleeve gastrectomy or the gastric bypass both use stapling devices to both cut the stomach and to seal it, so a patient could possibly develop a leak where fluid actually leaks out between the staples. A leak is the most common cause of death from either a sleeve gastrectomy or a gastric bypass. The leak rate nationwide is somewhere around 2-3%. However, the leak rate at well established and experienced practices is generally about 0.5%.
Other complications include developing an intestinal obstruction, something that may occur in a gastric bypass at the rate of about 1% but occurs even more rarely in a sleeve gastrectomy or a lap band. Another type of complication that could occur with any surgery is blood clots that can break off and travel to the lungs or brain. Patients who are morbidly obese have a much higher risk of developing blood clots.