Comparison of Quadratus Lumborum Block and Rectus Sheath Block for Postoperative Analgesia in Single-Port Laparoscopic Adnexal Surgery: A Randomized Controlled Trial

Abstract

Background and Objectives: Regional anesthesia is a key component of multimodal analgesia following minimally invasive gynecologic surgery. However, single-port laparoscopic adnexal surgery differs anatomically and physiologically from multiport or open approaches, particularly in terms of incision site, tissue handling, and pain characteristics. Despite its increasing use, evidence supporting procedure-specific regional analgesic protocols for this approach remains limited. This study aimed to compare the analgesic efficacy of quadratus lumborum block (QLB) and rectus sheath block (RSB) in this surgical context. Materials and Methods: In this randomized controlled trial, 68 patients undergoing single-port laparoscopic adnexal surgery were randomly assigned to receive either QLB or RSB at the end of surgery. Four patients were excluded due to missing patient-controlled analgesia (PCA) data, resulting in 64 patients analyzed (QLB group: n = 32; RSB group: n = 32). The primary outcome was cumulative opioid consumption over the first 24 postoperative hours. Secondary outcomes included interval-based opioid consumption, time to first PCA bolus, postoperative pain scores, and incidence of postoperative nausea and vomiting (PONV). Results: The RSB group demonstrated significantly lower cumulative opioid consumption at 24 h postoperatively (132.9 [61.3, 338.4] µg vs. 453.0 [253.1, 811.0] µg, p < 0.001). This trend persisted across most postoperative time points up to 48 h. Interval-based opioid consumption was also lower in the RSB group during 0-24 h and 32-48 h intervals (each comparison p < 0.05). The time to first PCA bolus was significantly longer in the RSB group (56.5 [41.0, 340.3] minutes vs. 40.5 [33.3, 68.8] minutes; p = 0.014), and Kaplan-Meier analysis confirmed a delayed first bolus request in the RSB group (log-rank p = 0.007). Pain scores and postoperative nausea and vomiting incidence were comparable between groups. Conclusions: Compared with QLB, RSB provided similar pain relief with significantly lower opioid consumption following single-port laparoscopic adnexal surgery. These findings highlight the potential advantages of RSB in enhancing analgesic efficiency and support the development of procedure-specific regional analgesia protocols tailored to this surgical approach.

Keywords: hysterectomy; laparoscopic; nerve block; postoperative pain; quadratus lumborum block; single-port.

Figure 1

Ultrasound images illustrating the quadratus lumborum block (QLB) and rectus sheath block (RSB). (A) Before the injection of local anesthetic for QLB. (B) After injection, showing the spread of local anesthetic around the quadratus lumborum muscle, with visible accumulation between the middle and anterior layers of the thoracolumbar fascia. (C) Before the injection of local anesthetic for RSB. (D) After injection, the local anesthetic spreads between the posterior aspect of the rectus abdominis muscle and the posterior rectus sheath. ARS: anterior rectus sheath, EOM: external oblique muscle, ESM: erector spinae muscle, IOM: internal oblique muscle, PMM: psoas major muscle, PRS: posterior rectus sheath, QLM: quadratus lumborum muscle, RAM: rectus abdominis muscle, TAA: transversus abdominis aponeurosis, TAM: transversus abdominis muscle, TF and PP: transversalis fascia and parietal peritoneum, TLF: thoracolumbar fascia.

Figure 2

Consort Flow Diagram.

Figure 3

Kaplan–Meier survival curves showing the time to first patient-controlled analgesia bolus in the QLB and RSB groups. The RSB group exhibited a delayed first PCA request compared to the QLB group, indicating prolonged initial analgesic effect. A significant difference was observed between the two groups (log-rank p = 0.007). PCA: patient-controlled analgesia.