This study is designed as a prospective multicenter randomized controlled clinical trial comparing two surgical techniques of distal gastric bypass (DGB) in revisional surgery following failed Roux-en-Y gastric bypass. Patients will be randomly allocated 1:1 to A) DGB with lengthening of the BPL (DGB type I) or B) DGB with extended AL (DGB type II). Randomisation is stratified for participating center. The study will be performed in a clinical and out-patient setting with regular visits at 1.5, 3, 6, 12, 18, 24 and 36 months post intervention. The study will be set up as a multicenter study with bariatric centers: St. Antonius hospital, Groene Hart hospital, OLVG, Rijnstate hospital, Elisabeth Twee-steden Hospital, Bravis hospital, Medisch Centrum Leeuwarden, Catharina Hospital.

Rationale: Up to 35% of morbidly obese patients undergoing Roux-en-Y gastric bypass (RYGB) fail to lose sufficient weight or regain excessive weight after initial weight loss. Currently, there is no standardized approach to revisional surgery after failed RYGB. Distalisation of the RYGB limbs (DGB), with shortening of the common channel and extending either the alimentary limb (AL) or biliopancreatic limb (BPL), can be performed as revisional surgery to induce additional weight loss. To date, there is no general consensus as to optimal surgical technique or limb lengths to be used in distalisation of RYGB in both literature as well as clinical practice.

Objective: The aim of this study is to investigate the effect of two distalisation techniques of a gastric bypass in revisional surgery with standardised limb lengths in total weight loss (TWL) and the need for treatment for protein calorie malnutrition (PCM). In this randomised controlled trial DGB with lengthening of the BPL (DGB type I) will be compared to DGB with extended AL (DGB type II) in order to conclude which surgical technique is the optimal therapeutic strategy as revision surgery following Roux-en-Y gastric bypass.

Study design: A multicentre randomised controlled trial.

Study population: Morbidly obese patients with insufficient weight loss or weight regain following primary RYGB, who are eligible for distalisation surgery.

Intervention: A total of 150 participants will be randomised over two treatment groups: group A will undergo DGB type I and group B will undergo DGB type II.

Main study endpoints: Primary endpoints: %TWL 1 year after treatment and need for treatment of PCM. Secondary endpoints: weight loss, co-morbidity remission, PCM grading (debilitating defecation patterns, temporary total parenteral nutrition treatment, revision, mortality), morbidity, nutritional deficiencies, quality of life and patient satisfaction.

Inclusion Criteria:

• Age 18-65 years;
• BMI ≥40 kg/m2 or BMI ≥35 kg/m2 with obesity related comorbidity;
• Weight regain or insufficient weight loss (EWL<50% or TWL<20%)15,16 following RYGB;
• Multidisciplinary team screening at one of the bariatric centres;
• Informed consent and willing to enter the follow-up program.

Exclusion Criteria:

• Failed Roux-en-Y gastric bypass due to anatomic, surgical reasons (gastric pouch dilatation >50 mL, gastro-gastric fistula, gastro-jejunostomy);
• Distalisation of RYGB is technical infeasible (judgment by surgeon);
• Inflammatory bowel disease, celiac disease, irritable bowel syndrome and other causes of chronic diarrhea;
• Severe concomitant disease (such as carcinomas and neurodegenerative disorders);
• Pregnant women;
• Noncompliance in follow-up or unwilling to undergo surgery;
• Inability of reading/understanding and filling out questionnaires.

Patients who meet the eligibility criteria will be included in this trial at the outpatient clinic of the participating bariatric centres after informed consent is obtained. The participating patients will be randomised into one of the surgical techniques: type I or type II DGB. Randomisation will take place in the operating room through an internet-based randomisation system in REDCap. Only the participants are blinded to the treatment allocation. The randomisation table will be created by an independent epidemiologist in the St. Antonius hospital, ensuring concealment of treatment allocation. Participants will be randomised in equal numbers to both interventions. The randomisation will be stratified by participating hospitals to ensure participants are evenly allocated to each treatment arm at each participation hospital.