Clinical effectiveness of transversus abdominis plane (TAP) blocks for pain relief after caesarean section: a meta-analysis

Background: The effectiveness of transversus abdominis plane (TAP) blocks for acute pain relief after caesarean section, in comparison to normal practice, remains uncertain.

Methods: Electronic literature databases were searched from inception to May 2016 for randomised controlled trials that assessed the effectiveness of TAP blocks following caesarean section. Trials were eligible if comparisons were made against no block or placebo, and/or intrathecal morphine. Risk of bias was assessed using the Cochrane tool. Data for consistent outcomes were subject, where possible, to meta-analysis and presented as either mean differences with 95% confidence intervals or incidence of a particular event.

Results: Twenty published studies fulfilled our inclusion criteria. TAP blocks significantly reduced pain at rest both when compared with placebo or no TAP blocks (-0.96, 95% CI -1.67 to -0.25, P=0.008) and intrathecal morphine (1.10, 95% CI 0.59 to 1.60, P<0.0001). Both these comparisons showed the greatest improvement with pain on movement, (-1.58, 95% CI -2.69 to -0.47, P=0.005 and 1.35, 95% CI 0.76 to 1.94, respectively, P<0.00001). Morphine consumption was significantly reduced with TAP blocks when compared to placebo or no TAP blocks (-15.88, 95% CI -22.02 to -9.73, P<0.00001). This significance was lost when TAP blocks were both compared to intrathecal morphine (0.89, 95% CI -0.64 to 2.43, P=0.25) and given in co-administration (0.00, 95% CI -0.10 to 0.10, P=1.00).

Conclusion: TAP blocks provide effective analgesia after caesarean section; however, additional benefits are more difficult to demonstrate when long-acting intrathecal opioids are administered.