The analgesic effect of transversalis fascia plane block after caesarean section under spinal anaesthesia with intrathecal morphine: a randomised controlled trial

We aimed to test whether bilateral injection of bupivacaine 0.25% in the transversalis fascia plane reduced 24 h opioid dose after singleton caesarean section, under spinal anaesthesia with intrathecal morphine, compared with saline 0.9% injectate. We allocated randomly 52 women to bilateral injection of 20 ml saline 0.9% on arrival in the post-anaesthesia care unit and 54 women to bilateral injection of 20 ml bupivacaine 0.25% (with adrenaline 2.5 mu g.ml(-1)). Mean (SD) cumulative morphine equivalent opioid dose 24 h after saline injection was 32.3 (28.3) mg and 18.7 (20.2) mg after bupivacaine injection, a mean (95%CI) difference of 13.7 (4.1-23.2) mg (p = 0.006). Median (IQR [range]) time to first postoperative opioid dose was 3.0 (1.5-10.3 [0.0-57.4]) h after saline 0.9% and 8.2 (2.7-29.6 [0.2-55.4]) h after bupivacaine 0.25% (p = 0.054). Transversalis fascia plane with bupivacaine 0.25% with adrenaline reduced postoperative pain at rest during 48 h (0-10-point scale) by a mean (95%CI) of 0.9 (0.2-1.6) points (p = 0.013) and on movement by 1.2 (0.4-2.1) points (p = 0.004). We conclude that transversalis fascia plane bupivacaine 0.25% with adrenaline reduces pain and opioid dose after caesarean section compared with saline 0.9%.