Comparative study of transversus abdominis nerve block with rectus sheath nerve block in pain control after laparoscopic cholecystectomy

To compare transversus abdominis plane block (TAP block) with rectus sheath block (RSB) for pain control after elective laparoscopic cholecystectomy.

Single center, parallel group, randomized controlled trial; total sample size 60; allocation ratio 1 to 1; phase not applicable; individual simple randomization using sequentially numbered opaque sealed envelopes. Participants, postoperative clinical staff, data collectors, outcome assessors and statisticians are blinded; the block performer is not blinded.

Imam Khomeini Hospital Complex; blocks performed under ultrasound guidance; identical dressings applied; outcomes recorded at prespecified time points.

Adults aged 20 to 60 years; American Society of Anesthesiologists physical status I or II (ASA); body mass index 18 to 35; elective laparoscopic cholecystectomy; written informed consent. Main exclusion criteria: refusal; allergy to local anesthetics; coagulopathy; local infection at the injection site; alcohol or substance misuse; major psychiatric disorder; significant chronic painful disease; failed block; operative time more than 3 hours; intraoperative complications.

Group A receives ultrasound guided TAP block with 20 mL bupivacaine 0.25 percent after induction of general anesthesia and before incision. Group B receives ultrasound guided RSB with 20 mL bupivacaine 0.25 percent at the same time point. Perioperative anesthesia and postoperative analgesia are standardized in both groups.

ain intensity by visual analogue scale (VAS) at 2, 6, 12 and 24 hours after surgery; cumulative opioid consumption within 24 hours; need for intraoperative fentanyl and recovery ketorolac; block related complications.

In this randomized clinical trial, eligible patients will be allocated after confirmation of the inclusion/exclusion criteria and obtaining written informed consent. Participants will be assigned using simple randomization with a 1:1 allocation ratio to one of the following two groups: the TAP block group (transversus abdominis plane block) and the rectus sheath block group. 1) Randomization method Type of randomization: Simple randomization (without blocking and without stratification). For each participant, an independent random assignment will be generated and allocated to one of two groups (A/B). Quasi-random methods (e.g., alternating assignment, date of birth, medical record number, day of visit, etc.) will not be used. 2) Unit of randomization Unit: Individual randomization; each patient constitutes an independent unit for allocation. Cluster or multilevel randomization will not be performed in this study. 3) Stratification Stratified randomization will not be used. All eligible participants will enter the randomization process without stratification. 4) Randomization tools Random sequence generation tool: Computer-generated random numbers using SPSS. Allocation implementation at the bedside: Sequentially numbered, opaque, sealed envelopes (SNOSE). 5) Generation of the random sequence The allocation sequence will be generated by an individual independent of the clinical implementation team. A list of assignments with a length equal to the required sample size will be created, and for each entry, allocation to A or B will be generated with equal probability (0.5/0.5). The final output will be a serial list in which each sequential number corresponds to a specific allocation (A/B). 6) Allocation concealment To minimize selection bias, allocation concealment will be ensured using the SNOSE method. Envelopes will be opaque, light-impermeable, sealed, and sequentially numbered. Each envelope will contain a card indicating the group code (A = TAP, B = Rectus Sheath). Envelopes will be prepared by an independent person and stored securely. The envelope will be opened only after final confirmation of patient eligibility and documentation of written informed consent.

To minimize bias, participants, postoperative care staff, data collectors, and outcome assessors will be blinded to group allocation. The blocks will be performed after induction of general anesthesia, and identical dressings will be applied over the injection sites. Group allocation will be implemented using sequentially numbered, opaque, sealed envelopes (SNOSE) and will be disclosed only to the anesthesiologist performing the block; in documents accessible to outcome assessors, allocation will be recorded only as code A/B. The postoperative pain management protocol will be identical and pre-standardized in both groups. Statistical analyses will be conducted using coded groups, and unblinding will take place only after database lock.