Abdominal Pain After Bariatric Surgery and the Role of the Gut: A Review

Obesity is a major health concern, affecting over 1 in 8 people worldwide. Bariatric surgery (BS) is currently the most effective long-term treatment for morbid obesity. In addition to sustained weight loss, BS is beneficial in treating obesity related comorbidities including dyslipidemia and type 2 diabetes (T2DM). The beneficial effects of BS are a result of weight loss and surgery-induced shifts in the gut microbiota and its metabolites. At the same time, BS may also lead to complications and side effects. Abdominal pain is one of the most frequently reported complaints after BS with a prevalence of 33.8-54.4% within this patient group. However, in many patients the abdominal pain remains unexplained beyond gallstones, internal herniation, and ulcers. This raises the question whether the gut microbiota itself may play a direct role in the pathophysiology of unexplained abdominal pain. Over the years several studies have shown changes in the gut microbiota and related metabolites after BS. These include increased gut microbial diversity and altered microbial composition after BS. Higher abundances of Proteobacteria and Fusobacteria are reported, while a decrease in butyrate-producing Firmicutes is reported. Along with these changes in microbiota, BS causes higher plasma bile acid levels and altered short-chain fatty acid (SCFA) profiles. These metabolic shifts are believed to support weight control, glucose regulation, and lipid metabolism. More recently, specific microbial taxa and metabolite profiles were linked to abdominal complaints following BS. This suggests that dysbiosis and metabolites may play a role in unexplained abdominal pain after BS.