Diarrhea after bariatric procedures, mainly those with malabsorptive elements including Roux-Y Gastric Bypass and Biliopancreatic Diversion, is common and an essential determinant of quality of life and micro- and macronutrient deficiencies. Bariatric surgery is the only sustainably successful method to address morbid obesity and its comorbidities, particularly gaining more and more importance in the specific treatment of diabetic patients. Approximately half a million procedures are annually performed around the world, with numbers expected to rise drastically in the near future. A multitude of factors exert their influence on bowel habits; preoperative comorbidities and procedure-related aspects are intertwined with postoperative nutritional habits. Diagnosis may be challenging owing to the characteristics of post-bariatric surgery anatomy with hindered accessibility of excluded segments of the small bowel and restriction at the gastric level. Conventional testing measures, if available, generally yield low accuracy and are usually not validated in this specific population. Limited trials of empiric treatment are a practical alternative and oftentimes an indispensable part of the diagnostic process. This review provides an overview of causes for chronic post-bariatric surgery diarrhea and details the particularities of its diagnosis and treatment in this specific patient population. Topics of current interest such as the impact of gut microbiota and the influence of bile acids on morbid obesity and especially their role in diarrhea are highlighted in order to provide a better understanding of the specific problems and chances of future treatment in post-bariatric surgery patients.
Keywords: Bariatric surgery; Bile acids and salts; Blind loop syndrome; Diarrhea; Dumping syndrome; Gut microbiota; Malabsorption; Malnutrition; Steatorrhea.