Biliopancreatic limb length impacts metabolic dysfunction-associated steatotic liver disease trajectories after Roux-en-Y gastric bypass.

BACKGROUND: RYGB is an effective treatment option for metabolic dysfunction-associated steatotic liver disease (MASLD). The optimal configuration for the biliopancreatic limb (BPL) remains uncertain. OBJECTIVES: To assess whether BPL length in Roux-en-Y gastric bypass (RYGB) affects improvement in MASLD. SETTING: University Hospital Center. METHODS: We conducted a retrospective cohort study of adults who underwent RYGB between 2019 and 2024. Patients were dichotomized a priori by BPL length: ≈70 cm (short) versus ≥100 cm (long). Outcomes were evaluated at baseline, 3 months (3M), 1 year (1Y), and 2 years (2Y) postoperatively. Primary outcomes were MASLD-related noninvasive tests (NITs) including the Nonalcoholic Fatty Liver Disease (NAFLD) Fibrosis Score (NFS) and Noninvasive Nonalcoholic Steatohepatitis Detection Score (NI-NASH DS). RESULTS: Compared with short BPL, long BPL was associated with lower NI-NASH DS at 3M (-1.19; 95% confidence interval [CI], -1.93 to -.48; q < .01) and 1Y (-.77; 95% CI, -1.37 to -.15; q < .05) and lower NFS at 1Y (-.39; 95% CI, -.70 to -.09; q < .05) and 2Y (-.53; 95% CI, -.96 to -.10; q < .05). Glycated hemoglobin was lower at 1Y (-.10; 95% CI, -.20 to .00; q < .05) and 2Y (-.20; 95% CI, -.30 to -.00; q < .05), while total weight loss was similar. Total cholesterol and low-density lipoprotein cholesterol were lower at 1Y and 2Y. Nutritional markers were largely comparable. CONCLUSIONS: A longer BPL (≥100 cm) was associated with greater improvements in MASLD-related NIT trajectories at 1Y and 2Y after RYGB, with better glycemic control and similar weight loss, without evidence of nutritional deficiency.