Background and Objectives Effective postoperative analgesia after cesarean delivery enhances early recovery, ambulation, and breastfeeding. In a previous study, we established the effectiveness of the quadratus lumborum block in providing pain relief after cesarean delivery compared with patient-controlled analgesia (morphine). In the current study, we hypothesized that this method would be equal to or better than the transversus abdominis plane block with regard to pain relief and its duration of action after cesarean delivery.

Methods Between April 2015 and August 2015, we randomized 76 patients scheduled for elective cesarean delivery under spinal anesthesia to receive the quadratus lumborum block or the transversus abdominis plane block for postoperative pain relief. This trial was registered prospectively (NCT 024489851).

Results Patients in the quadratus lumborum block group used significantly less morphine than the transversus abdominis plane block group (P < 0.05) at 12, 24, and 48 hours but not at 4 and 6 hours after cesarean delivery. This group also had significantly fewer morphine demands than the control group (P < 0.05) at 6, 12, 24, and 48 hours after cesarean delivery. No significant differences in visual analog scale results were shown between the 2 groups at rest or with movement. Calculated total pain relief at rest and with movement were similar (P < 0.001) in both groups.

Conclusions The quadratus lumborum block was more effective in reducing morphine consumption and demands than transversus abdominis plane blocks after cesarean section. This effect was observed up to 48 hours postoperatively.