Ultrasound-guided bilateral quadratus lumborum block vs. intrathecal morphine for postoperative analgesia after cesarean section: a randomized controlled trial

BACKGROUND: Adequate pain control after cesarean section (CS) is crucial for mothers caring for newborns, and early ambulation to avoid thromboembolism and chronic abdominal and pelvic pain. This randomized controlled trial compared the efficacy of quadratus lumborum block (QLB) and intrathecal morphine (ITM) for analgesia after CS. METHODS: Ninety women at ≥ 37 weeks pregnancy scheduled for elective CS were enrolled. All patients received spinal anesthesia and post-operative QLB. They were randomly allocated to Control (anesthesia: 0.1 ml saline, QLB: 24 ml saline), ITM (anesthesia: 0.1 mg morphine, QLB: 24 ml saline), or QLB groups (anesthesia: 0.1 ml saline, QLB: 24 ml 0.375% ropivacaine). Integrated analgesia score (IAS) and numerical rating scale (NRS) scores at rest and during movement, morphine requirements in the first 48 h, time to first morphine dose and morphine-related side effects were recorded. RESULTS: IASs and NRS scores at rest and during movement were significantly lower in QLB and ITM group than in Control group. Moreover, IASs and NRS scores at rest and during movement were lower in QLB group than in ITM group. Time to first morphine dose was significantly longer in QLB group than in ITM and Control group. Furthermore, morphine requirements in the first 48 h were significantly lower in QLB group than ITM and Control group. Incidence of morphine-related side effects was significantly higher in ITM group than in QLB and Control group. CONCLUSIONS: QLB and ITM are effective analgesic regimens after CS. However, QLB provides better long-lasting analgesia and reduced total postoperative morphine consumption.