Background: Anastomotic complications after laparoscopic Roux-en-Y gastric bypass (LRYGB) including leaks, ulceration, and stenosis remain a significant cause of post-operative morbidity and mortality. Our objective was to compare two different surgical techniques regarding short-term anastomotic complications.

Methods: A retrospective analysis of all patients operated with a primary LRYGB from 2006 to June 2015 in one institution, where prospectively collected data from an internal quality registry and medical journals were analyzed.

Results: In total, 2420 patients were included in the analysis. 1016 were operated with a technique where the mesentery was divided during the creation of the Roux-limb (DM-LRYGB) and 1404 were operated with a method where the mesentery was left intact (IM-LRYGB). Leakage in the first 30 days [2.6% vs. 1.1% (p < 0.05)], and ulceration or stenosis occurring during the first 6 months after surgery [5.6% vs. 0.1% (p < 0.05)] was significantly higher in the DM-LRYGB group. Adjusted odds ratio for anastomotic leak was 0.46 (95% CI 0.24-0.87) and for stenosis/ulceration 0.01 (95% CI 0.002-0.09).

Conclusion: IM-LRYGB seems to reduce the risk of complications at the anastomosis. A plausible explanation for this is that the blood supply to the anastomosis is compromised when the mesentery is divided.