Proximal Roux-en-Y gastric bypass: Addressing the myth of limb length.

Background: Some studies suggest that changes in weight or metabolic outcomes are affected by the lengths of the gastrointestinal limbs in the Roux-en-Y gastric bypass.

Methods: Participants (N = 1,770) underwent primary Roux-en-Y gastric bypass and were followed ≤7 years in the Longitudinal Assessment of Bariatric Surgery-2, a multicenter US cohort study. Alimentary limb and biliopancreatic limb lengths were measured according to research protocol; common channel was measured in a subsample (N = 547). Aimentary limb, biliopancreatic limb, and common channel ratio to total small bowel length were calculated.

Results: Median presurgery body mass index was 46 (25th-75th percentile: 43-51) kg/m. Medians (25th-75th percentiles) for alimentary limb length were 125 cm (100-150), for biliopancreatic limb length were 50 cm (50-60), and common channel length were 410 cm (322-520). Statistics for ratios to the small bowel length were 0.23 (0.18-0.27) for alimentary limb, 0.09 (0.07-0.10) for biliopancreatic limb, and 0.69 (0.63-0.73) for common length. There were no significant associations between alimentary limb, biliopancreatic limb, common channel, alimentary limb ratio, biliopancreatic limb ratio or common channel ratio, and either weight loss or improvement in cardiometabolic outcomes.

Conclusion: The common channel length in Roux-en-Y gastric bypass is highly variable between individuals. None of the limb lengths in this study, nor alimentary limb, biliopancreatic limb, or common channel ratios, seem to be related to weight loss or metabolic improvements >7 years.