Meta-analysis of the success of block following combined spinal-epidural vs epidural analgesia during labour

Observational studies suggest that combined spinal-epidural analgesia (CSE) is associated with more reliable positioning, lower epidural catheter replacement rates, and a lower incidence of unilateral block compared with epidural analgesia. However, evidence from high-quality trials still needs to be assessed systematically. We performed a systematic review that included 10 randomised controlled trials comparing CSE and epidural analgesia in 1722 labouring women in labour. The relative risk of unilateral block was significantly reduced after CSE vs epidural analgesia (0.48, 95% CI 0.24-0.97), but significant between-study heterogeneity was present (I-2=69%, p=0.01). No differences were found for rates of epidural catheter replacement, epidural top-up, and epidural vein cannulation. On the basis of current best evidence, a consistent benefit of CSE over epidural analgesia cannot be demonstrated for the outcomes assessed in our review. A large randomised controlled trial with adequate power is required.