Lateral QL Block vs Intrathecal Morphine for Cesarean Section

Effective postoperative analgesia after cesarean delivery is essential for maternal recovery, early mobilization, breastfeeding, and maternal-infant bonding. Although intrathecal morphine (ITM) is considered the gold standard for post-cesarean analgesia, its use is associated with opioid-related adverse effects. Ultrasound-guided lateral quadratus lumborum block (QLB-I) has emerged as a promising alternative. This randomized, double-blind, non-inferiority trial aims to compare the postoperative analgesic efficacy of lateral QLB-I with ITM. Secondary outcomes include postoperative opioid consumption, pain scores, opioid-related adverse effects, quality of recovery (ObsQoR-11T), and maternal satisfaction.

Inclusion Criteria: * Women aged between 18 and 45 years. * Singleton term pregnancy (≥37 weeks of gestation). * American Society of Anesthesiologists (ASA) physical status II. * Scheduled to undergo elective cesarean delivery via a Pfannenstiel incision. * Planned to receive spinal anesthesia for cesarean delivery. * Provision of written informed consent following a comprehensive explanation of the study. * Sufficient cognitive capacity to understand and complete the study assessment instruments, including the Numeric Rating Scale (NRS) and the ObsQoR-11T. Exclusion Criteria: * Known allergy or hypersensitivity to any of the study medications, including morphine, bupivacaine, or fentanyl. * Coagulopathy (international normalized ratio \[INR\] \>1.5 or platelet count \100 mg/day). * Infection, hematoma, or skin lesion at the planned block insertion site. * Diagnosis of preeclampsia, eclampsia, or HELLP syndrome. * Placenta previa, placenta accreta spectrum, or placental abruption. * Gestational diabetes mellitus or chronic hypertension. * Emergency cesarean delivery indicated because of fetal distress. * Conversion to general anesthesia during cesarean delivery. * History of chronic pain syndrome (e.g., fibromyalgia, lumbar disc herniation, or neuropathic pain). * Regular use of opioids or psychotropic medications within the preceding 3 months. * Diagnosis of epilepsy, severe anxiety disorder, or major depressive disorder. * Obesity (body mass index \>35 kg/m²). * Severe systemic disease, including New York Heart Association (NYHA) class III or IV heart failure, hepatic or renal failure, advanced respiratory disease, or obstructive sleep apnea. * Advanced pulmonary disease requiring continuous positive airway pressure (CPAP) therapy. * Inadequate spinal anesthesia or the requirement for supplemental intraoperative analgesia. * Surgical duration exceeding 120 minutes. * Excessive intraoperative blood loss (≥1,000 mL) or the need for blood transfusion.