The incidence of morbid obesity is increasing constantly. One of the most common complications related to obesity is represented by non-alcoholic fatty liver disease that can range from fatty liver to non-alcoholic steatohepatitis, which is progressively becoming the first cause of end-stage liver disease and need for liver transplantation with alcohol hepatitis. Moreover, many factors contribute to an elevated incidence of morbid obesity in the post-transplant setting and individuals with obesity undergoing liver transplantation rarely succeed in losing weight postoperatively. Individuals with obesity in the pre- and post-transplant setting benefit from weight loss with reduced morbidity and mortality. Bariatric surgery is effective in inducing weight loss and obesity-related medical problems resolution but its application in the liver transplant setting is limited.

The aim of this systematic review and meta-analysis is to explore postoperative morbidity and mortality of bariatric surgery performed before, during, or after liver transplantation.

This is a systematic review and proportion meta-analysis of 24 studies based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guideline.

Bariatric surgery performed in patients with obesity and end-stage liver disease waiting for liver transplantation is associated with a 5% major post-bariatric surgery complications rate and a 7% 1-year post-liver transplantation mortality. Patients who had bariatric surgery for morbid obesity after liver transplantation had a 16% post-bariatric surgery major complication rate. For patients undergoing simultaneous bariatric surgery and liver transplantation, meta-analysis was not applicable but the review of the literature found 1/10 patients experiencing major postoperative bariatric-related complications and 31/32 patients were alive 1 year after operation.

Bariatric surgery must be performed in selected cases in the setting of liver transplantation. Simultaneous bariatric surgery and liver transplantation are associated with low morbidity and mortality while bariatric surgery after liver transplantation showed increased morbidity. Bariatric surgery before LT is feasible and can improve liver function for patients in transplant waiting list.