Comparison of Quadratus Lumborum Block Types in Open Gynecologic Surgery

This prospective observational study was conducted to observe and analyze postoperative acute pain outcomes in patients undergoing open gynecologic surgery with a Pfannenstiel incision. The study included patients who received quadratus lumborum block (QLB) techniques as part of routine perioperative analgesic management. Quadratus lumborum blocks were performed using ultrasound guidance according to standard clinical practice. The block was administered with the patient in the lateral position, and a high-frequency linear ultrasound transducer was used to identify the quadratus lumborum muscle and surrounding anatomical structures. For Quadratus Lumborum Type 1 (lateral) block, local anesthetic was injected at the anterolateral border of the quadratus lumborum muscle. For Quadratus Lumborum Type 2 (posterior) block, local anesthetic was deposited posterior to the quadratus lumborum muscle, within the thoracolumbar fascial plane. The selection of Quadratus Lumborum Type 1 or Type 2 block was determined solely by the attending anesthesiologist based on routine clinical considerations, surgical characteristics, and patient-related factors. No intervention or regional analgesia technique was assigned by the investigators for the purpose of this study, and study participation did not influence anesthetic management. Participants would have received the same anesthetic and regional analgesia techniques in the same manner and intensity regardless of study enrollment. Postoperative acute pain outcomes were prospectively collected and analyzed between predefined exposure groups according to the routinely applied quadratus lumborum block technique. The investigators did not modify clinical practice, dosing, timing, or performance of regional anesthesia. All anesthetic and analgesic interventions were provided as part of standard medical care. This study was approved by the local ethics committee as an observational study and was conducted in accordance with institutional standards of care.