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

Background The effectiveness of Transversus Abdominis Plane (TAP) block in the provision of acute pain relief after Caesarean Section, in comparison to normal practice, remains uncertain. This systematic review examines the published randomised evidence. Methods Electronic literature databases were searched from inception to November 2015 for randomised controlled trials that assessed the effectiveness of TAP block 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 meta-analysed where possible and presented as either mean differences with 95% confidence intervals or incidence of a particular event. Results Nineteen published studies fulfilled our inclusion criteria, of which nine compared TAP block with placebo TAP and all but one were blinded. TAP block significantly reduced pain at rest 6 hours after caesarean section when compared with placebo or no TAP block (-3.58; 95% CI -6.27 to -0.90 p=0.009) however, this effect diminished at 24 hours (-1.05; 95% CI -2.08 to -0.01p=0.05). Morphine consumption is significantly reduced with TAP block usage. Co-administration of intrathecal morphine and TAP block significantly improved pain at rest and on movement in the short term (-0.54; 95% CI -1.00 to -0.08 p=0.02) and (-1.02; 95% CI -1.66 to -0.39 p=0.002) respectively, compared to placebo TAP block and intrathecal morphine. Conclusions TAP block provides effective analgesia after Caesarean Section, however additional benefits of TAP block are more difficult to demonstrate when long acting intrathecal opioids are administered