Analgesic benefits of pre-operative versus postoperative transversus abdominis plane block for laparoscopic cholecystectomy: a frequentist network meta-analysis of randomized controlled trials

Background: Transversus abdominis plane (TAP) block has been utilized to alleviate pain following laparoscopic cholecystectomy (LC). However, the optimal timing of administration remains uncertain. This study aimed to compare the efficacy of pre-operative and postoperative TAP blocks as analgesic options after LC. Methods: A frequentist network meta-analysis of randomized controlled trials (RCTs) was conducted. We systematically searched PubMed (via the National Library of Medicine), EMBASE, Scopus, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science up to March 2023. The study included RCTs that enrolled adult patients (≥ 18 years) who underwent LC and received either pre-operative or postoperative TAP blocks. The primary outcome assessed was 24-hour postoperative morphine consumption (mg). Additionally, pain rest scores within 3 hours, 12 hours, and 24 hours, as well as postoperative nausea and vomiting (PONV), were considered as pre-specified secondary outcomes. Results: A total of 34 trials with 2317 patients were included in the analysis. Postoperative TAP block demonstrated superiority over the pre-operative TAP block in reducing opioid consumption (MD 2.02, 95% CI 0.87 to 3.18, I2 98.6%, p < 0.001). However, with regards to postoperative pain, neither pre-operative nor postoperative TAP blocks exhibited superiority over each other at any of the assessed time points. The postoperative TAP block consistently ranked as the best intervention using SUCRA analysis. Moreover, the postoperative TAP block led to the most significant reduction in PONV. Conclusions: The findings suggest that the postoperative TAP block may be slightly more effective in reducing 24-hour postoperative opioid consumption and PONV when compared to the pre-operative TAP block. Trial registration: PROSPERO, CRD42023396880 .