The analgesic efficacy of transversus abdominis plane block vs. wound infiltration after inguinal and infra-umbilical hernia repairs: A systematic review and meta-analysis with trial sequential analysis

BACKGROUND: Both transversus abdominis plane (TAP) block and wound infiltration with local anaesthetic have been used to relieve pain after inguinal or infra-umbilical hernia repair. OBJECTIVES: To determine whether TAP block or local anaesthetic infiltration is the best analgesic option after inguinal or infra-umbilical hernia repair. DESIGN: Systematic review and meta-analysis with trial sequential analysis. DATA SOURCES: MEDLINE, Embase, Cochrane Central Register of Controlled Clinical Trials, Web of Science, up to June, 2020. ELIGIBILITY CRITERIA: We retrieved randomised controlled trials comparing TAP block with wound infiltration after inguinal or infra-umbilical hernia repair. Primary outcome was rest pain score (analogue scale 0 to 10) at 2 postoperative hours. Secondary pain-related outcomes included rest pain score at 12 and 24 h, and intravenous morphine consumption at 2, 12 and 24 h. Other secondary outcomes sought were block-related complications such as rates of postoperative infection, haematoma, visceral injury and systemic toxicity of local anaesthetic. RESULTS: Seven trials including 420 patients were identified. There was a significant difference in rest pain score at 2 postoperative hours in favour of TAP block compared with wound infiltration, with a mean (95% confidence interval) difference of −0.8 (−1.3 to -0.2); I(2) = 85%; P = 0.01. Most secondary pain-related outcomes were also significantly improved following TAP block. No complication was reported. The overall quality of evidence was moderate. CONCLUSION: There is moderate level evidence that TAP block provides superior analgesia compared with wound infiltration following inguinal or infra-umbilical hernia repair. TRIAL REGISTRY NUMBER: PROSPERO CRD42020208053.