Transversus abdominis plane block for analgesia after Cesarean delivery: a systematic review and meta-analysis

To assess the efficacy of transversus abdominis plane (TAP) block in improving analgesia following Cesarean delivery (CD). We searched MEDLINE, CENTRAL, EMBASE, and CINAHL for randomized controlled trials that assessed the efficacy of TAP block following CD and reported on postoperative pain scores and/or opioid consumption. Studies were combined according to the use or non-use of intrathecal morphine (ITM). Another analysis was performed for studies comparing TAP block with ITM. Nine studies were included. Transversus abdominis plane block significantly reduced opioid consumption (mg morphine equivalents) after Cesarean delivery at six hours (mean difference [MD] -10.18; 95% confidence interval [CI] -13.03 to -7.34), at 12 hr (MD -13.83; 95% CI -22.77 to -4.89), and at 24 hr (MD -20.23; 95% CI -33.69 to -6.77). The TAP block also reduced pain scores for up to 12 hr and nausea in patients who did not receive ITM. When added to ITM, TAP block produced a small reduction in pain scores on movement in the first six hours (MD -0.82, 95% CI -1.52 to -0.11). When compared with ITM, pain scores on movement and opioid consumption at 24 hr were lower (MD 0.98; 95% CI 0.06 to 1.91 and MD 8.42 mg; 95% CI 1.74 to 15.10, respectively), and time to first rescue analgesic was longer with ITM (8 hr vs 4 hr), although opioid-related side effects were more common. Transversus abdominis plane block significantly improved postoperative analgesia in women undergoing CD who did not receive ITM but showed no improvement in those who received ITM. Intrathecal morphine was associated with improved analgesia compared with TAP block alone at the expense of an increased incidence of side effects.