Lateral QL Block vs Intrathecal Morphine for Cesarean Section

Condition(s) studied

Investigational drug(s) / intervention(s)

Lateral Quadratus Lumborum Block: Active Lateral QLB Local anesthetic: 0.25% bupivacaine, 0.4 mL/kg perside (maximum 30 mL per side). Maximum total dose: Bupivacaine ≤2.5 mg/kg (maximum approximately 150 mg). Timing: Immediately after completion of surgery. The patient will be positioned supine or in a slight lateral decubitus position. A high-frequency linear US transducer (5-12 MHz) will be placed on the anterolateral abdominal wall at the T12-L1 level. The fascial plane will be identified under ultrasound guidance. A 22-gauge, 100-mm needle will be advanced using an in-plane approach, and after negative aspiration, the local anesthetic will be injected incrementally with hydrodissection confirming correct spread. Sham ITM: The spinal anesthesia technique will be identical to that of the active ITM group. Morphine will be replaced with 0.2 mL preservative-free normal saline, while maintaining an identical syringe volume (2.7 mL) and appearance.

ıv morphine PCA: A standardized IV PCA protocol will be initiated for all patients using a PCA device (Body Guard 575 pain manager, UK), programmed to deliver morphine boluses of 0.01-0.015 mg/kg (IBW), with a 6-minute lockout and a 4-hour maximum dose of 0.1-0.15 mg/ kg (IBW). No basal infusion will be used.

Intrathecal morphine: Hyperbaric 0.5% bupivacaine 12.5 mg, fentanyl 20 µg, and morphine 80 µg (0.08 mg). Spinal anesthesia will be performed at the L3-L4 or L4-L5 intervertebral space using a 25-gauge Quincke spinal needle. The study solution will be prepared to a total volume of 2.7 mL. Sham QLB Following completion of surgery, the patient will be positioned in the lateral decubitus position. The ultrasound transducer will be placed over the lateral QLB scanning window. A 22-gauge needle will be advanced into the skin and subcutaneous tissue only, without entering the fascial plane. To maintain procedural standardization and preserve blinding, 1-2 mL of normal saline will be injected into the subcutaneous tissue. Procedure duration, patient positioning, ultrasound probe placement, and dressing application will be identical to those used for the active lateral QLB-I procedure. A sterile dressing will be applied at the end of the procedure.

Study summary

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.

Eligibility

Primary outcome measure(s)

• Cumulative equivalent morphine consumption in the first 24 hours after surgery — postoperative day 1
  The total dose of morphine administered via the patient-controlled analgesia (PCA) device, together with all rescue opioids administered during the first 24 postoperative hours following surgery, will be converted to morphine milligram equivalents (MME) using validated conversion factors and summed.

Trial sites (1)

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