While sleeve gastrectomy (SG) results in sustained weight loss for the majority of patients, some will experience inadequate weight loss or weight regain requiring revision. The objective of this study was to evaluate differences in weight loss over time between patients undergoing Roux-en-Y gastric bypass (RYGB) or single anastomosis duodenoileostomy (SADI) after SG.

We queried a single institution’s bariatrics registry to identify patients who underwent RYGB or SADI after previous SG over a three-year period. Demographics, operative characteristics, and post-operative complications were evaluated. Interval total body weight loss (TBWL) and excess body weight loss (EBWL) were calculated from available follow-ups within 2 years.

We identified 124 patients who underwent conversion to RYGB (n = 61) or SADI (n = 63) following previous SG. There were no differences in sex, age, or medical comorbidities between groups. The median initial BMI was higher in the SADI group (44.9 vs. 41.9 for RYGB, p = 0.03) with greater excess body weight (56.7 vs. 64.3 kg, p = 0.04). The SADI group had a shorter median operative duration (157 vs. 182 min for RYGB, p < 0.01) and lower readmission rates (0 vs. 14.75%, p < 0.01). There was no difference in post-operative complications or need for rehydration therapy between the groups. Among 122 patients (98.4%) that had follow-up weights available, there were no differences in TBWL between groups. RYGB patients had a higher EBWL at 2, 3, and 6 months (p < 0.05 for all comparisons), but there were no differences between RYGB and SADI at 1 or 2 years.

Both RYGB and SADI conversions proved effective for further weight loss following failed SG at our academic center. While neither demonstrated clear superiority in long-term (> 1 year) weight loss, RYGB’s restrictive gastric pouch may explain its early weight loss advantage.