Audit of transverse abdominus plane block for analgesia following caesarean section

A retrospective audit was undertaken to investigate the clinical impression that transversus abdominis plane block is a worthwhile analgesic adjunct following lower uterine segment caesarean section, performed under spinal anaesthesia with intrathecal morphine (100–150 μg). The North East Health Ethics Committee (Vic., Australia) approved the project as audit. Audit data for 20 Transversus Abdominis Plane blocks were compared to 20 cases without Transversus Abdominis Plane blocks. Bilateral Transversus Abdominis Plane blocks were performed after skin closure using ultrasound guided placement of 20 ml ropivacaine 0.5% to each side. Paracetamol and diclofenac were routinely prescribed analgesics, with oxycodone 10 mg or tramadol 50–100 mg used to treat breakthrough pain. Audit data gathered, included time from surgery to first opioid use and analgesia requirement. The mean (SD) time to first oxycodone use was significantly longer for patients receiving Transversus Abdominis Plane blocks [9.1 (6.2) h vs 4.3 (2.7) h, p = 0.003]; and the median [range] oxycodone requirement in the first 24 h was significantly less (22.5 mg [10–50] vs 40 mg [20–60], p = 0.024). Other analgesic use was not significantly different. One patient in each group required parenteral morphine. This audit shows that ultrasound guided Transversus Abdominis Plane blocks are feasible following lower uterine segment caesarean section; and that there is analgesic benefit when given in addition to intrathecal morphine. Our technique is different to McDonnell et al. [1], as we use ultrasound to guide placement of the Transversus Abdominis Plane block, and they did not use intrathecal morphine. As intrathecal morphine is not without risk or morbidity, research is required to determine if Transversus Abdominis Plane blocks after lower uterine segment caesarean section can provide equivalent analgesia to intrathecal morphine, especially if catheters are placed for continuous infusion.