Tailored One Anastomosis Gastric Bypass (OAGB-TL)

July 21, 2025 updated by: Shmuel Kivity, MD, Tel-Aviv Sourasky Medical Center

Tailoring One-Anastomosis Gastric Bypass Based on Total Small Bowel Length - A Randomized Controlled Trial

One Anastomosis Gastric Bypass (OAGB) is the most common metabolic and bariatric surgery (MBS) in Israel, recognized for its effectiveness in achieving sustainable weight loss and mitigating obesity-related diseases. The metabolic outcomes of OAGB are significantly influenced by the length of the biliopancreatic limb (BPL). The objective of this study is to determine whether tailoring the BPL length to the total small bowel length (TSBL) results in more effective weight loss compared to patients undergoing OAGB with a fixed BPL of 180 cm. Efficacy and safety of this approach will also be evaluated, ensuring it does not lead to long-term morbidity or negatively impact patients' quality of life.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Scientific Background and Rationale for the Study One-Anastomosis Gastric Bypass (OAGB) is the most common bariatric procedure in Israel [1]. Over the years, OAGB has been proven to be an effective surgery, yielding significant and sustained weight loss, improvement in obesity-related comorbidities, and a relatively low failure rate [2].

The procedure involves separating a long gastric pouch from the remaining stomach and creating an anastomosis between the pouch and a distant loop of the small intestine [3]. Since this procedure bypasses a relatively long intestinal segment (typically 150-200 cm), it results in malabsorption of carbohydrates, fats, proteins, and other nutrients. This malabsorption-related mechanism leads to greater weight loss compared to purely restrictive surgeries like sleeve gastrectomy [4].

The length of the bypassed segment, specifically the biliopancreatic limb (BPL), plays a critical role in determining the metabolic outcomes of OAGB. A longer BPL is associated with more significant weight loss and greater improvement in obesity-related diseases [5]. However, the ideal BPL length remains a topic of global debate. Some experts recommend measuring the total small bowel length (TSBL) or ensuring at least 250-300 cm of common channel (CC) to prevent pathological malabsorption in patients with a shorter bowel and to reduce the risk of weight regain in those with a longer bowel [3,6].

Currently, the most widely accepted approach is to standardize the BPL length at 150-200 cm, as studies have shown that this range minimizes the risk of nutritional deficiencies [7]. However, tailoring the BPL length to the patient's TSBL is an increasingly recognized strategy that may optimize outcomes by ensuring a more precise CC length, thereby reducing complications and improving long-term weight loss.

Study Objective To evaluate whether tailoring the BPL length to the TSBL results in more effective weight loss compared to a standard bypass length of 180 cm.

Study Endpoints BPL and TSBL lengths Weight progression during follow-up Postoperative nutritional complications Improvement in obesity-related comorbidities Study Participants Single-center cohort: 200 patients Multi-center cohort: 500 patients Participating centers: Ichilov Medical Center, Assuta Tel Aviv, Herzliya Medical Center Participant Recruitment and Informed Consent Process

Eligible participants (competent adults) will be invited to sign a digital informed consent form via the PM7 system. The process includes:

A face-to-face explanation Time for consideration An opportunity to ask questions The signed consent form will be stored digitally in PM7 and printed as needed. If digital signing is not possible, a paper form will be used. The process adheres to Regulation 169 and follows an updated consent protocol. Enrollment and consent will take place during the preoperative consultation at the bariatric clinic.

Inclusion Criteria Patients aged 18 and older scheduled for OAGB at Tel Aviv Sourasky Medical Center Exclusion Criteria Special populations - Patients under 18, pregnant women, individuals lacking decision-making capacity, etc.

Previous bariatric surgery Withdrawal Criteria TSBL < 450 cm, as this would prevent achieving a common channel length of at least 250-300 cm, increasing the risk of severe malabsorption and nutritional deficiencies (protein, vitamins, iron).

Study Methods and Design Randomization Process After enrollment and consent, participants will be randomly assigned to either the intervention or control group.

Surgical Interventions Intervention Group: The surgeon will manually measure TSBL intraoperatively and create a BPL equal to 40% of the TSBL. This ensures a minimum CC length of 250-300 cm, in line with standard OAGB recommendations.

Control Group: The surgeon will measure the TSBL but will create a fixed BPL of 180 cm, as per the current standard.

Postoperative Follow-Up Patients will undergo routine follow-up at 2 weeks, 1, 3, 6, and 12 months, and annually thereafter.

Data Collection and Privacy Identifiable patient information will be separated from the dataset by an authorized investigator.

The principal investigator will maintain the coding key in a password-protected file within the hospital network.

Data will remain within the hospital and not be shared externally. Statistical Analysis T-tests and chi-square tests will be used to compare baseline characteristics. Results will be reported in tables with standard deviation and p-values. Study Timeline and Duration Total study duration: 8 years from approval.

Study Type

Interventional

Enrollment (Estimated)

500

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Israel
      • Tel Aviv, Israel
        • Recruiting
        • Tel Aviv Sourasky Medical Center

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Adults (≥18 years) undergoing OAGB

Exclusion Criteria:

  • Patients <18 years, pregnant women, or those lacking decision-making capacity Prior bariatric surgery Short bowel (<450 cm)

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: Control group BPL 180 cm
Total bowel length measure and BPL will be 180 cm regardless of total small bowel length
Procedure: Control - BPL 180 cm
Total bowel length measure and BPL will be180 cm
Experimental: Tailored BPL length
Total bowel length measure and BPL will be 40% of total bowel length ensuring at least 250 cm common channel
Procedure: Tailored BPL length
Total bowel length measure and BPL will be 40% of total bowel length ensuring at least 250 cm common channel

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
weight loss
Time Frame: 6 months, one year, and 3 years after surgery
Total weight loss will be calculated as - preoperative weight-last follow-up weight/preoperative weight * 100
6 months, one year, and 3 years after surgery

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Postoperative nutritional complications
Time Frame: 6 months and one year after surgery
Postoperative nutritional complications - albumin, vitamins, iron
6 months and one year after surgery
resolution of obesity related diseases
Time Frame: 6 months and one year postopertively

Resolution of obesity related diseases - Type 2 diabetes, hypertension, hyperlipidemia.

Resolution of diseases definition - If patients no longer required medications or other treatment methods prior to surgery. In case of type 2 diabetes, a value of Hba1c below 6.5% in addition to cessation of antidiabetic to define its resolution.
6 months and one year postopertively
Bariatric Analysis and Reporting Outcome System score
Time Frame: 6 months and one year postopertively

Bariatric Analysis and Reporting Outcome System score - quality of life assessment.

The assessment will be as follows - ≥7.0 - Excellent 5.1 - 6.9 - Very Good 3.1 - 5.0 - Good 1.1 - 3.0 - Fair

≤1.0 - Failure Maximum score - 9 (in case of optimal condition and no complications occur) Minimum scire - Negative values (if severe complications occur).
6 months and one year postopertively
Fecal Score
Time Frame: 6 months, 1 year and 3 years
Altered bowel habits-such as loose stools, increased frequency of defecation, and even fecal incontinence-can significantly impact quality of life following bariatric surgery. To evaluate these changes, we are using the semi-quantitative Stool Frequency and Consistency Score, also known as the Fecal Score (FS), to assess bowel movement patterns at 6, 12, and 36 months postoperatively. The FS (Fecal Score) is calculated based on fecal frequency and consistency. Fecal frequency is assessed using a 5-point scale: less than twice per week (1 point), every two days (2 points), once daily (3 points), twice daily (4 points), and more than twice daily (5 points). Fecal consistency is also scored on a 5-point scale: watery stools (5 points), loose stools (4 points), normal stools (3 points), firm stools (2 points), and hard stools associated with constipation (1 point). The FS is derived by summing the fecal frequency and consistency scores.
6 months, 1 year and 3 years

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Tel-Aviv Sourasky Medical Center

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 29, 2025

Primary Completion (Estimated)

January 31, 2029

Study Completion (Estimated)

January 31, 2029

Study Registration Dates

First Submitted

February 11, 2025

First Submitted That Met QC Criteria

February 11, 2025

First Posted (Actual)

February 17, 2025

Study Record Updates

Last Update Posted (Actual)

July 24, 2025

Last Update Submitted That Met QC Criteria

July 21, 2025

Last Verified

July 1, 2025

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • TLV-0586-24

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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