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Caesarean delivery is common and can cause severe postoperative pain but injection of local anaesthetic at various sites for regional blocks or local anaesthetic infiltration may reduce this. We aimed to compare and rank these sites. We searched PubMed, Google Scholar, EMBASE and CENTRAL to June 2021 for randomised controlled trials and performed a random-effects Bayesian model network meta-analysis. The primary outcome was dose of parenteral morphine equivalents in the first 24 postoperative hours. We used surface under cumulative ranking probabilities to order techniques. We analysed 114 trials (8730 participants). The ordered mean (95% credible interval) reduction in morphine equivalents, from 34 mg with placebo, were as follows: ilio-inguinal 15 (1-32) mg; ilio-inguinal-iliohypogastric 13 (6-19) mg; transversalis fascia 11 (4-26) mg; erector spinae 11 (10-32); transverse abdominis 9 (4-13) mg; wound catheter infusion 8 (2-15) mg; quadratus lumborum 8 (1-15) mg; wound infiltration 8 (2-13) mg; and no intervention -4 (-10 to 2) mg. Ordered efficacies for injection sites were different for other relevant outcomes, including pain (to 4-6 h and to 24 h) and time to rescue analgesia: there was no single preferred route of injection. The ordered mean (95% credible interval) reduction in dynamic pain scores (0-10 scale) at 24 h compared with placebo were as follows: wound infusion 1.2 (0.2-2.1); erector spinae 1.3 (-0.5 to 3.1); quadratus lumborum 1.0 (0.1-1.8); ilio-inguinal-iliohypogastric 0.6 (-0.5 to 1.8); transverse abdominis 0.6 (-0.1 to 1.2); wound infiltration 0.5 (-0.3 to 1.3); transversalis fascia -0.8 (-3.4 to 1.9); ilio-inguinal -0.9 (-3.6 to 1.7); and no intervention -0.8 (-1.8 to 0.2). We categorised our confidence in effect sizes as low or very low.
Singh et al. (Mon,) studied this question.