20.500.12556/DiRROS-27777 Alterations in gut microbiota after upper gastrointestinal resections should we implement screening to prevent complications? Background: Surgical procedures and alterations of the gastrointestinal (GI) tract increase the risk of small intestinal bacterial overgrowth (SIBO), which is associated with GI symptoms and complications that compromise postoperative recovery. However, the prevalence and clinical impact of SIBO after various upper GI surgical procedures remain poorly understood. Objective: This study aimed to evaluate the prevalence of SIBO after different types of upper GI surgery and to investigate the associated clinical factors. Methods: We conducted an observational study involving 157 patients with a history of upper GI surgery: Roux-en-Y gastric bypass (RYGB), laparoscopic single-anastomosis gastric bypass (OAGB), subtotal (STG) or total gastrectomy (TG), subtotal (SP)or total pancreatectomy (TP), cephalic duodenopancreatectomy (WR), and small bowel resection for Crohn’s disease. A glucose–hydrogen breath test was performed, and demographic, clinical, and treatment-related data were collected. Statistical analyses included t-tests, non-parametric tests, ANOVA, and correlation analyses using R software. Results: At a median follow-up of 25.7 ± 18.1 months, 31% (48/157) of patients tested positive for SIBO. The highest prevalence was observed after RYGB and OAGB (43%), followed by TG (30%), STG (29%), TP/WR (28%), and Crohn’s disease bowel resection (19%). No cases of SIBO were observed after SP. SIBO positivity was significantly associated with bloating and flatulence (p = 0.002), lactose intolerance (p = 0.047), systemic sclerosis (p = 0.042), T2D (p = 0.002), and exposure to adjuvant chemotherapy (p = 0.001) and radiotherapy (p = 0.027). In addition, the risk of SIBO increased proportionally with the duration of GI resection or exclusion (p = 0.013). Conclusions: In our study, the prevalence of SIBO after upper GI surgery was 31%, with the highest incidence (43%) observed in metabolic surgery patients. Importantly, adjuvant radio/chemotherapy was associated with an increased risk of SIBO, and extensive small bowel resection or exclusion was strongly associated with an increased risk of SIBO. Furthermore, the limitations of current diagnostic methods, which lack sufficient sensitivity and specificity, highlight the importance of early screening and standardization of diagnostic techniques to improve patient management and outcomes. small intestinal bacterial overgrowth gut dysbiosis intestinal microbiota upper GI surgery glucose–hydrogen breath test exocrine pancreatic insufficiency pancreatic cancer gastric cancer Crohn’s disease metabolic bariatric surgery postoperative complications true false true Angleški jezik Ni določen Neznano 2026-02-24 14:29:34 2026-02-24 14:29:35 2026-02-25 03:50:50 0000-00-00 00:00:00 2025 0 0 Nasl. z nasl. zaslona; Opis vira z dne 22. 10. 2025; str. 1-16 no. 10, [article no.] 1822 Vol. 61 2025 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 616.3 1648-9144 10.3390/medicina61101822 254266115 RAZ_Novljan_Urska_2025.pdf RAZ_Novljan_Urska_2025.pdf 1 025B529D09B1D3E7E333C4E08E5B38B0 d73a783eaa3f087a888d4293af8bbd55f2576ddba3a70b46f8170a3d6651433c 0448cc3a-1185-11f1-9cb0-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=40832 https://doi.org/10.3390/medicina61101822 0 13a05dca-1185-11f1-9cb0-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=40833 Univerzitetni klinični center Ljubljana 0 0 0