BACKGROUND: Despite the increasing use of bariatric surgery as the most effective treatment of morbid obesity, there is still no consensus on its preoperative diagnostic workup. The aim of this study was to identify the pathologies of the endoscopic and radiologic investigations before performing bariatric surgery and to evaluate their impact on the patient management.METHODS: Retrospective analysis of prospectively collected data of 1225 consecutive patients who underwent laparoscopic Roux-en-Y gastric bypass (n = 834) or sleeve gastrectomy (n = 391) at our institution. An abdominal ultrasound was performed in 1188 patients, 1190 patients underwent upper gastrointestinal (GI) endoscopy, 1178 patients underwent upper GI series, and 610 patients underwent esophageal manometry.SETTING: Private hospital, Switzerland.RESULTS: Gallstones were detected in 222 (21.0%) patients, and a synchronous cholecystectomy was performed in 220 (18.0%) patients. The upper GI series indicated hiatal hernias in 325 (27.6%) patients. The most common findings of the upper GI endoscopy were type-C gastritis (224 patients, 18.8%), reflux esophagitis (229 patients, 19.2%), Helicobacter pylori-positive gastritis (158, 13.3%), and hiatal hernia (55 patients, 4.6%). Additionally, we detected 1 Barrett's high-grade dysplasia, 2 Barrett's carcinomas, and 1 stomach cancer in asymptomatic patients, who were scheduled to have a sleeve gastrectomy. Esophageal motility disorders were detected in 104 (17.0%) individuals, who underwent esophageal manometry.CONCLUSIONS: We recommend performing abdominal sonography and upper GI endoscopy before bariatric surgery as they reveal findings, which influence the therapeutic approach. Upper GI series and esophageal manometry help to define patients not suitable for sleeve gastrectomy.