Title : Efficacy of adjuvants used in Transversus Abdominis Plane (TAP) blocks for abdominal surgeries: A systematic review and meta-analysis of randomized controlled trials
Abstract:
Background: Transversus abdominis plane (TAP) blocks are regional anesthesia techniques that provide somatic analgesia to the anterior abdominal wall. Delivered under ultrasound or laparoscopic guidance, TAP blocks are increasingly used in abdominal surgeries to reduce postoperative pain, enhance recovery, and minimize opioid use in both elective and emergency procedures. Adjuvants such as dexamethasone, clonidine, and dexmedetomidine are commonly added to local anesthetic solutions in TAP blocks to prolong analgesia and improve pain control. When administered via ultrasound- or laparoscopic-guided TAP catheters, these agents reduce opioid consumption, nausea, and pain scores. However, the optimal adjuvant choice remains unclear, with limited high-quality comparative data available.
Objective: To evaluate the efficacy and safety of adjuvants used in transversus abdominis plane (TAP) blocks in adult patients undergoing abdominal surgery, through a systematic review and meta-analysis of randomized controlled trials.
Methods: A systematic search of the Cochrane Library and Embase databases was conducted for randomized controlled trials (RCTs) published between January 2000 and June 2025 evaluating the use of transversus abdominis plane (TAP) blocks with or without adjuvants in adult abdominal surgery. Study selection followed PRISMA guidelines. The primary outcome was identification of the most frequently used adjuvants in clinical practice. Secondary outcomes included postoperative pain scores, opioid consumption, length of hospital stay, and cost data to evaluate overall clinical efficiency. Risk of bias for included studies will be assessed using the Cochrane Risk of Bias 2.0 tool. Where appropriate, meta-analyses will be performed using a random-effects model to pool continuous and dichotomous outcomes. Heterogeneity will be assessed using the I² statistic, and publication bias will be evaluated via funnel plots.
Results: This is an ongoing systematic review and meta-analysis. To date, 2,291 records have been identified through database searching and are undergoing screening and assessment. The study aims to include only randomized controlled trials investigating the use of adjuvant agents in TAP blocks for adult patients undergoing abdominal surgery. Data extraction and analysis are currently pending.
Keywords: TAP block, regional anesthesia, postoperative pain, abdominal surgery, adjuvants, systematic review, meta-analysis
