Rectus Sheath Block Versus Transversus Abdominis Plane Block for Analgesia in Laparoscopic Bariatric Surgery (RSB-TAPB)

May 13, 2026 updated by: Kittitorn Supphapipat, MD, Chiang Mai University

Comparison of Rectus Sheath Block and Transversus Abdominis Plane Block for Analgesia in Laparoscopic Bariatric Surgery: A Randomized Controlled Trial

This randomized controlled trial aims to compare the analgesic efficacy of rectus sheath block (RSB) and transversus abdominis plane block (TAPB) in patients undergoing laparoscopic bariatric surgery. Both techniques are regional anesthesia methods used as part of multimodal analgesia to reduce postoperative pain and opioid requirements.

Eligible participants will be randomly assigned to receive either a RSB or a TAPB after general anesthesia. Postoperative pain scores, opioid consumption, recovery outcomes, area of sensory loss, time to first rescue analgesia, and block-related adverse events will be assessed and compared between the two groups.

This study will help determine which regional anesthesia technique provides more effective postoperative analgesia for laparoscopic bariatric surgery

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

Laparoscopic bariatric surgery provides sustained weight loss for patients with obesity and is associated with improved metabolic outcomes and increased life expectancy. Despite its minimally invasive approach, laparoscopic bariatric surgery is often associated with moderate-to-severe postoperative pain, which may require significant opioid use. Postoperative opioid administration may increase the risk of opioid-related adverse effects, including opioid-induced ventilatory depression and postoperative nausea and vomiting. These concerns are particularly important in patients with obesity, who may have an increased risk of obstructive sleep apnea and opioid-related respiratory complications.

Enhanced Recovery After Surgery principles recommend opioid-sparing strategies, including regional anesthesia and local anesthetic techniques, as part of multimodal analgesia for bariatric surgery. Several regional analgesic techniques have been used for laparoscopic bariatric surgery, including local infiltration analgesia, transversus abdominis plane block, rectus sheath block, and other fascial plane blocks.

Transversus abdominis plane block is commonly used for abdominal surgery and provides somatic analgesia to the anterolateral abdominal wall. However, its analgesic efficacy in laparoscopic bariatric surgery remains variable, partly due to differences in block technique, injection site, local anesthetic regimen, and technical challenges in patients with obesity. Excessive subcutaneous tissue may make identification of the target fascial plane more difficult and may increase the risk of inaccurate needle placement or incomplete sensory blockade.

Rectus sheath block is another regional anesthesia technique used for abdominal surgery. It involves the injection of local anesthetic between the rectus abdominis muscle and the posterior rectus sheath, providing analgesia to the anterior abdominal wall, particularly around the midline and periumbilical region. Rectus sheath block may be technically easier to perform than transversus abdominis plane block in patients with obesity because of its more superficial needle trajectory. Previous studies suggest that rectus sheath block may reduce postoperative pain and opioid consumption compared with systemic analgesia alone or local infiltration analgesia.

Although both rectus sheath block and transversus abdominis plane block may improve postoperative analgesia after laparoscopic bariatric surgery, their relative efficacy remains unclear. No previous study has directly compared these two techniques for postoperative analgesia in this surgical population.

This randomized controlled trial will compare the analgesic efficacy and opioid-sparing effects of ultrasound-guided rectus sheath block (RSB) and ultrasound-guided transversus abdominis plane block (TAPB) in patients undergoing laparoscopic bariatric surgery. Eligible participants will be randomly assigned to receive either RSB or TAPB as part of perioperative multimodal analgesia.

The study will assess postoperative pain intensity, opioid consumption, quality of recovery, rescue analgesic requirements, and block-related adverse events. The primary analysis will evaluate whether one technique provides superior analgesia. If superiority is not demonstrated, equivalence will be assessed. The findings may help guide the selection of regional anesthesia techniques for postoperative analgesia in patients undergoing laparoscopic bariatric surgery.

Study Type

Interventional

Enrollment (Estimated)

96

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 Contact Backup

Study Locations

  • Thailand
    • Mueang
      • Chiang Mai, Mueang, Thailand, 50200
        • Maharaj Nakorn Chiang Mai Hospital, Faculty of Medicine, Chiang Mai University
        • Contact:
        • Contact:
        • Principal Investigator:
          • Artid Samerchua, MD
        • Principal Investigator:
          • Kittitorn Supphapipat, MD

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

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Patients aged 20-60 years old
  • Scheduled for elective LBS including laparoscopic sleeve gastrectomy, proximal jejunal bypass, and Roux-en-Y gastric bypass
  • American Society of Anesthesia (ASA) physical status III
  • Have ability to communicate and understand the study and accept to participate in the study

Exclusion Criteria:

  • Patients who have following underlying disease: severe hepatic impairment [diagnosed of cirrhosis (Child-Pugh C)], coagulopathy (diagnosed of disease associated with abnormal coagulation), pre-existing neurological deficits, chronic pain (diagnosed of chronic pain disease or current use regular analgesic drugs), or any drug addiction.
  • Known allergy to bupivacaine or weighing less than 60 kg, as the planned doses of bupivacaine may exceed safe maximum limits.
  • Patient with previous foregut surgery including esophageal, gastric, liver and pancreases resection.

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: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Rectus Sheath Block Group
Participants in this group will receive bilateral ultrasound-guided rectus sheath block using 30 mL of 0.25% bupivacaine with epinephrine 5 µg/mL on each side, in addition to standard perioperative multimodal analgesia.
Procedure: Rectus Sheath Block
Bilateral rectus sheath block will be performed by an anesthesiologist experienced in ultrasound-guided regional anesthesia. The ultrasound probe will be positioned at the midpoint between the xiphoid process and the umbilicus along the mid-clavicular line. After aseptic preparation of the puncture site and ultrasound probe, a needle will be advanced using an in-plane, lateral-to-medial approach under continuous ultrasound guidance. After correct needle-tip placement between the rectus abdominis muscle and the posterior rectus sheath, 30 mL of 0.25% bupivacaine with epinephrine 5 µg/mL will be injected on each side after negative aspiration. Local anesthetic spread will be monitored in real time, and the procedure will be repeated on the contralateral side using the same technique.
Active Comparator: Transversus Abdominis Plane Block Group
Participants in this group will receive bilateral ultrasound-guided transversus abdominis plane block using 30 mL of 0.25% bupivacaine with epinephrine 5 µg/mL on each side, in addition to standard perioperative multimodal analgesia.
Procedure: Transversus Abdominis Plane Block
Bilateral transversus abdominis plane block will be performed by an anesthesiologist experienced in ultrasound-guided regional anesthesia. The ultrasound probe will be placed on the lateral abdominal wall between the costal margin and iliac crest at the mid-axillary line. Depth, frequency, and gain will be adjusted to clearly visualize the fascial plane between the internal oblique and transversus abdominis muscles. After aseptic preparation of the puncture site and ultrasound probe, a needle will be advanced using an in-plane approach under continuous ultrasound guidance. After correct needle-tip placement in the transversus abdominis plane, 30 mL of 0.25% bupivacaine with epinephrine 5 µg/mL will be injected on each side after negative aspiration. Local anesthetic spread within the fascial plane will be monitored in real time, and the procedure will be repeated on the contralateral side using the same technique.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Pain intensity during movement at 6 hours postoperatively (Pain-move-6hour)
Time Frame: 6 hours postoperatively
Pain intensity will be assessed using the Numerical Rating Scale (NRS), an 11-point scale ranging from 0 to 10, where 0 indicates no pain and 10 represents the worst pain imaginable. Patients will be asked to rate their pain intensity by selecting the number that best reflected their level of pain during movement at 6 h postoperatively. Patients will be instructed to perform a standardized movement (including coughing, deep breathing, or changing position from supine to sitting) and then rate the pain intensity experienced during that movement.
6 hours postoperatively

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Pain intensity at rest and during movement
Time Frame: 0, 2, 6, 12, 24, and 48 hours postoperatively
Postoperative pain intensity will be assessed using the NRS. Pain scores will be recorded both at rest and movement at 0, 2, 6, 12, 24, and 48 hours (except for movement at 6 hours which was defined as primary outcome) (Pain-rest-0hour, Pain-rest-2hour, Pain-rest-6hour, Pain-rest-12hour, Pain-rest-24hour, Pain-rest-48hour and Pain-move-0hour, Pain-move-2hour, Pain-move-12hour, Pain-move-24hour, Pain-move-48hour) postoperatively. For pain at rest, patients will be asked to rate their pain while lying comfortably without active movement. For pain during movement, patients will be instructed to perform a standardized movement (including coughing, deep breathing, or changing position from supine to sitting) and then rate the pain intensity experienced during that movement.
0, 2, 6, 12, 24, and 48 hours postoperatively
Intraoperative fentanyl consumption
Time Frame: During intraoperative period
Total intraoperative fentanyl consumption will be recorded for each patient and expressed in microgram. Fentanyl will be administered to standard clinical practice. The cumulative dose of fentanyl administered from induction of anesthesia until the end of surgery will be extracted from the anesthesia record
During intraoperative period
Area of sensory loss
Time Frame: 30 minutes postoperatively
The area of sensory loss will be assessed by testing for loss of cold sensation using a cold stimulus (ice). Sensory testing will be performed over the anterior abdominal wall, and dermatomal coverage will be recorded and mapped according to patient-reported loss of cold sensation compared with the contralateral or adjacent non-blocked area.
30 minutes postoperatively
Time to first rescue analgesia
Time Frame: within 48 hours postoperatively
Time to first rescue analgesia will be defined as the interval, in minutes, from the end of surgery to the first activation (buttom press) of the patient-controlled analgesia (PCA) device. Data will be extracted from the PCA device electronic record
within 48 hours postoperatively
Postoperative opioid consumption
Time Frame: 0-24 hours and 24-48 hours postoperatively
Postoperative opioid consumption will be defined as the cumulative dose of opioids administered during the postoperative period and will be expressed as intravenous morphine milligram equivalents (MME). All opioid doses administered via patient-controlled analgesia (PCA) will be extracted from PCA device logs and converted to MME using standard conversion factors
0-24 hours and 24-48 hours postoperatively
QoR-14
Time Frame: 24 and 48 hours postoperatively
Postoperative quality of recovery will be assessed using the Thai version of the 14-item Quality of Recovery questionnaire (QoR-14), a validated patient-reported outcome measure. The QoR-14 evaluates multiple domains of postoperative recovery, including physical comfort, emotional state, physical independence, psychological support, and pain. Each item is scored on an 11-point numerical scale ranging from 0 to 10, yielding a total score from 0 to 140, with higher scores indicating a better quality of recovery.
24 and 48 hours postoperatively
Incidence and severity of nausea and vomiting
Time Frame: 0-2, 2-6, 6-12, 12-24 and 24-48 hours postoperatively.
The incidence and severity of postoperative nausea and vomiting will be assessed using a four-point numerical scale, where 0 = no nausea and vomiting, 1 = mild nausea, 2 = severe nausea or a single episode of vomiting, and 3 = more than one episode of vomiting.
0-2, 2-6, 6-12, 12-24 and 24-48 hours postoperatively.
Block-related complications
Time Frame: Perioperative period
Block-related complication will include the occurrence of hematoma, intra-abdominal puncture, and local anesthetic systemic toxicity (LAST).
Perioperative period

Collaborators and Investigators

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

Sponsor

Chiang Mai University

Investigators

  • Principal Investigator: Kittitorn Supphapipat, MD, Department of Anesthesiology, Faculty of Medicine, Chiang Mai University

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 (Estimated)

May 10, 2026

Primary Completion (Estimated)

December 31, 2030

Study Completion (Estimated)

June 30, 2031

Study Registration Dates

First Submitted

May 6, 2026

First Submitted That Met QC Criteria

May 13, 2026

First Posted (Actual)

May 18, 2026

Study Record Updates

Last Update Posted (Actual)

May 18, 2026

Last Update Submitted That Met QC Criteria

May 13, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • ANE-2568-0679

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

IPD Plan Description

Individual participant data will not be shared because this is a single-centre investigator-initiated study with a limited sample size, and the data contain potentially sensitive patient information. De-identified summary data may be made available upon reasonable request to the principal investigator

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

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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