Analgesic efficacy of ultrasound-guided transversus abdominis plane block after cesarean delivery: A systematic review and meta-analysis

Purpose: The meta-analysis is aimed to further access the analgesic efficacy of ultrasound-guided transversus abdominis plane (USG-TAP) block after cesarean section (CS).

Methods: Electronic databases were searched for eligible studies. Primary objectives were pain-related outcomes. Weighted mean differences (WMDs) or standardized mean differences (SMDs), as well as risk ratios (RRs) with 95% confidence intervals (CIs), were used to calculate estimates. Subgroup analyses were done based on whether USG-TAP blocks were performed with long-acting intrathecal opioids (ITO).

Results: A total of 17 studies were included. When compared with control groups (placebo or no blocks), USG-TAP block resulted in lower cumulative opioid consumption at 6 h (WMD: -8.32; 95% CI: -14.86, -1.79), 12 h (WMD: -10.75; 95% CI: -20.93, -0.57), and 24 h (WMD: -12.71, 95% CI: -21.28, -4.14). No significant differences were demonstrated among dynamic or resting pain scores. Patients in USG-TAP groups needed longer time to request first analgesic (WMD: 3.56; 95% CI: 1.43, 5.68) and showed a lower requirement of opioid rescue analgesia for breakthrough severe pain during 24 h (RR: 0.40; 95% CI: 0.18, 0.86). Subgroup analyses showed USG-TAP blocks did not afford additional benefit in the presence of intrathecal morphine. Also, reduced need for antiemetics after CS and higher maternal satisfaction were provided by USG-TAP blocks.

Conclusion: USG-TAP block can provide significantly effective analgesia for patients who underwent CS in the absence of long-acting ITO and therefore are worth promoting in the setting of long-acting ITO being unfeasible.