Reversal of Roux-en-Y Gastric Bypass: A Swedish National Cohort Study
Conditions: Gastric Bypass Surgery, Revisional Bariatric Surgery, Complications After Bariatric Surgery
Sponsor: Vrinnevi Hospital

Reversal of Roux-en-Y Gastric Bypass: A Swedish National Cohort Study  
Version: November 1st 2025 
OBJECTIVE  
To investigates incidence, indications, symptom relief, complications, and weight outcomes 
after Roux-en-Y gastric bypass (RYGB) reversal. 
 
METHODS 
Study Design and Setting 
This nationwide, multi-center, retrospective cohort study includes all patients undergoing 
reversal of RYGB in Sweden between 2007 and 2023. Patients are identified through the 
Scandinavian Obesity Surgery Registry (SOReg).  
SOReg, established in 2007, is a nationwide research and quality registry that captures 
bariatric procedures performed in Sweden. The registry undergoes regular validation and has 
been demonstrated to maintain high data quality, with an acquisition rate of more than 97%. 
At the time of the primary bariatric procedure patients are informed of SOReg, and that data 
may be used for research. They are informed of the possibility to opt-out at any time.  
Therefore, no written consent was obtained. Data were pseudonymized and analyzed at group 
level to ensure confidentiality. 
Participants 
Included patients are adults (≥ 18years) who underwent reversal of RYGB between 2007 and 
2023. Exclusion criteria are emergency reversal due to bowel ischemia, reversal following 
other bariatric procedures (e.g. gastric banding), or partial/functional reversals (e.g., gastro-
gastric fistula or anastomosis between the Roux-limb and gastric remnant, without full 
reversal of RYGB).  
Data Collection 
Data from SOReg is complemented with review of medical records. Registry data is collected 
from both the primary RYGB and the reversal procedure. Perioperative and postoperative 
complications are classified according to the Clavien–Dindo system, with major 
complications defined as ≥ grade IIIb (i.e. complications requiring intervention under general 
anesthesia or resulting in organ failure or death). 

Medical record review provides additional information on indications for reversal, diagnostic 
work-up, intraoperative findings, surgical details (e.g., resection of Roux limb, pyloroplasty), 
postoperative course, reinterventions, readmissions, weight changes, and follow-up until 24 
months. 
Symptom relief after RYGB reversal is assessed through review of follow-up records. 
Because the indications for the reversal frequently overlap, each symptom indicating reversal 
is evaluated independently. Outcomes are classified as no, partial, or complete improvement. 
Complete improvement is defined as full resolution of the index symptom (e.g., cessation of 
hypoglycemia, pain-free status without analgesics). Partial improvement denotes a clinically 
meaningful reduction in symptom severity or frequency that do not meet criteria for complete 
resolution. No improvement indicates persistent symptoms. 
Statistics 
Continuous variables are presented as mean ± standard deviation (SD) or median (range), and 
categorical variables as number (percentage). Between- and within-group comparisons are 
performed using Student’s t test for normally distributed continuous data. Categorical 
variables are analyzed using chi-square tests, with Fisher’s exact test applied when expected 
cell counts were <5. Odds ratios with 95% confidence intervals are calculated from 
crosstabulations where appropriate. A two-sided p-value <0.05 is considered statistically 
significant.  All statistical analyses are conducted using SPSS Statistics, version 30.0 (IBM 
Corp., Armonk, NY, US).