Background Advances in surgery have considerably lowered postoperative morbidity. However, infection remains a considerable morbidity factor. The aim of this review is to identify the potential benefit(s) of the perioperative administration of probiotics/synbiotics to patients undergoing abdominal surgery. Methods We searched PubMed, Scopus, Web of Science, and Cochrane library to identify randomized controlled trials (RCTs) that studied the perioperative administration of probiotics/synbiotics to patients undergoing abdominal surgery. Results Nine RCTs studying 733 patients were included in our review. The incidence of postoperative pneumonia, cholangitis, and any infections as well as the duration of postoperative hospital stay and length of antibiotic therapy were lower among patients receiving probiotics than in the control group [six RCTs, 355 patients, odds ratio (OR) 0.24, 95% confidence interval (CI) 0.09-0.68; three RCTs, 209 patients, OR0.18, 95% CI0.05-0.57; seven RCTs, 514 patients, OR 0.26, 95% CI 0.12-0.55; five RCTs, 313 patients, OR −2.70, 95% CI−5.15 to −0.25; four RCTs, 250 patients, OR −4.01, 95% CI−5.11 to −2.92, respectively], while the incidence of postoperative wound infection, urinary tract infection, intra-abdominal abscess, and mortality was not different between patients of the compared groups (six RCTs, 355 patients, OR0.52, 95% CI0.23-1.18; five RCTs, 313 patients, OR0.44, 95% CI0. four RCTs, 226 patients, OR0.44, nine RCTs, 685 patients, OR0.98, respectively). Conclusion The use of probiotics/synbiotics may reduce postoperative infections after abdominal surgery. This is a promising infection-preventive measure that may decrease morbidity, length of antibiotic therapy, duration of hospital stay, and pressure for emergence of antimicrobial resistance. However, the results of this meta-analysis should be interpreted with caution due to the significant heterogeneity of the studies included.
