Total Alimentary Limb Length Is Not Associated with Weight Loss Following Proximal Roux-en-Y Gastric Bypass

Abstract

Background: Standard Roux-en-Y gastric bypass (RYGB) typically manipulates the proximal portion of the small intestine, leaving a variable and unknown common channel and total alimentary limb length (TALL). Despite high variability in postoperative weight loss, the factors contributing to this variability remain unknown. Given the known variability in small intestinal length, this unmeasured variability in TALL may be associated with weight loss responses.

Objective: To test the hypothesis that TALL is associated with postoperative weight loss following primary laparoscopic Roux-en-Y gastric bypass (RYGB).

Setting: Vanderbilt University Medical Center; Nashville, Tennessee, USA.

Methods: A total of 329 patients were recruited for this observational study and consented to laparoscopic measurement of the entire small intestinal length at the time of primary RYGB. Of these patients, 208 had successful measurement of the small bowel length (SBL) and underwent RYGB with a fixed biliopancreatic limb length (BPL, 50 cm). Common channel length (CCL) was allowed to vary normally to test the association between TALL and postoperative weight loss.

Results: Follow-up rates were 77% at 6 months and 41% at 24 months. Average SBL was 592 cm (min = 390 cm, max = 910 cm), with a standard deviation of 107 cm that led to significant variation in CCL (shortest 190 cm, longest 730 cm). Regression was used to model weight loss and body mass index, as well as percent change from baseline, for each patient given the measured TALL and CCL. Despite significant variation in TALL, there were no clinically significant effects of TALL or CCL on weight loss up to 24 months.

Conclusions: With a fixed BPL, normal variation in TALL does not significantly contribute to weight loss variability following RYGB. Future studies are needed to better understand the importance of intestinal limb lengths in primary and revisional RYGB surgery.

Keywords: Bariatric surgery; Common channel; Observational study; Roux-en-Y gastric bypass; Small bowel length; Weight loss.