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This study evaluates postoperative analgesic outcomes of unilateral quadratus lumborum block and erector spinae plane block in patients undergoing unilateral lower abdominal surgery.

May 14, 2026Open Access

Analgesic Efficacy of Unilateral Quadratus Lumborum Block (Lateral Approach) compared with Erector Spinae Plane Block in Patients Undergoing Unilateral Lower Abdominal Surgery (Prospective Randomized Comparative Double-blinded Clinical Trial)

Key Points

This study evaluates postoperative analgesic outcomes of unilateral quadratus lumborum block and erector spinae plane block in patients undergoing unilateral lower abdominal surgery.
48 adult patients were randomized to receive either QLB (n=24) or ESPB (n=24) after induction of general anesthesia.
The primary outcome was total morphine consumption in the first 24 postoperative hours.
Analgesic outcomes, pain scores, and adverse events were assessed postoperatively.
Total morphine consumption was similar in the QLB (5.26 ± 2.17 mg) and ESPB (5.88 ± 2.51 mg) groups with p=0.376.
The time to first rescue analgesia was longer in the QLB group (2 hours) compared to the ESPB group (1 hour), p=0.251.
Pain scores at 24 hours were comparable (median VAS 3 for both groups, p=0.08).

Abstract

Introduction Ultrasound-guided truncal blocks such as quadratus lumborum (QLB) and erector spinae plane block (ESPB) are increasingly used for opioid-sparing analgesia. We aimed to evaluate the postoperative analgesic outcome of ultrasound-guided unilateral QLB (lateral approach) and ESPB for use in adult patients undergoing unilateral lower abdominal surgery. Methods In this randomized comparative clinical trial, 48 adult patients scheduled for unilateral lower abdominal surgery were randomized to receive QLB (n = 24) and ESPB (n = 24) following induction of general anesthesia. The primary outcome was total morphine consumption in the first 24 postoperative hours. Results There was no statistical difference for total morphine consumption between the QLB and ESPB groups (5.26 ± 2.17 mg vs. 5.88 ± 2.51 mg; p = 0.376). The median time to first rescue analgesia was greater in the QLB (2 hours 0–18) vs. the ESPB group (1 hour 0–21; p = 0.251). Pain scores were not different between groups at 2, 4, 8, 12, and 24 hours post-op (median Visual Analogue Scale (VAS) at 24h: 3 3–5 QLB, 3 2–3 ESPB; p = 0.08). There were no differences between groups with respect to hemodynamic parameters, adverse events (nausea and vomiting: 4 in the QLB group, 6 in the ESPB group; p > 0.05) or block performance times (median time: 10min for both). Discussion We consider the clinical role of QLB and ESPB as an effective component of multimodal analgesia in unilateral lower abdominal surgeries. They have a similar safety profile considering the technique and the opioid sparing effects, similar performance characteristics and complication rates, which together suggest both blocks are safe and well-tolerated anesthetic procedures that can be daily practices. Conclusion Both QLB and ESPB provide significant, safe, and comparable postoperative analgesia for patients undergoing unilateral lower abdomen surgery. QLB may provide a slight time benefit to analgesia onset. Trial Registration This study was prospectively registered on ClinicalTrials.gov (NCT05524038; principal investigator: Rana Ahmed Abdelghaffar), registration date: 1/9/ 2022.

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