The analgesic effectiveness of ilioinguinal-iliohypogastric block for caesarean delivery: A meta-analysis and trial sequential analysis

BACKGROUND: An effective analgesia strategy following caesarean delivery should be designed to improve fetomaternal outcomes. Much recent research has focused on the efficacy of ilioinguinal-iliohypogastric (II-IH) block for providing such analgesia. DESIGN: A systematic review and meta-analysis of randomised controlled trials. OBJECTIVES: To investigate the effectiveness of II-IH block in patients undergoing caesarean delivery. The primary outcome was the cumulative parenteral morphine equivalents at 24 h. Pain scores at 4 to 6 and 24 h postsurgery, time to first rescue analgesia and adverse effects were the secondary outcomes analysed. DATA SOURCES: Two reviewers searched independently PubMed, Embase, Google Scholar and the Cochrane central registers of a controlled trial from their inception until June 2020. METHODOLOGY: Prospective randomised control trials comparing II-IH block with either systemic analgesia alone or a placebo block (non-active controls) were eligible for inclusion. Only trials that reported their methods comprehensibly and transparently were included. Cochrane methodology was used to assess the risk of bias. Data are presented as mean difference with 95% confidence interval (CI). RESULTS: Thirteen trials comprising a total of 858 patients were included. Opioid (intravenous morphine equivalents) consumption was reduced by 15.57 mg (95% CI -19.87 to -11.28; P < 0.00001; I2 = 95%) during the first 24 h in patients receiving II-IH block when compared with placebo or no block. Patients receiving general anaesthesia showed a greater reduction in morphine requirement at 24 h than those receiving neuraxial anaesthesia. Adequate 'information size' for the above outcome was confirmed with trial sequential analysis to rule out the possibility of a false-positive result. II-IH also significantly reduced pain scores at rest more so at 4 to 6 h than at 24 h. CONCLUSIONS: Our study suggests that the use of II-IH blocks is associated with a lower 24 h requirement for intravenous morphine equivalents in patients undergoing caesarean delivery. However, given the methodological limitations, data should be interpreted with caution until more studies are available.