Anterior Quadratus Lumborum Block: A Scoping Review of Anatomical Rationale, Techniques, and Clinical Applications

INTRODUCTION: The anterior quadratus lumborum block (aQLB) is a fascial plane block targeting the interfascial plane between the quadratus lumborum and psoas major muscles, aiming to achieve both somatic and visceral analgesia through potential spread of local anesthetic toward the thoracolumbar nerve roots. Despite years of clinical use and a growing body of randomized trials across different surgical settings, uncertainty remains regarding its mechanisms of action, patterns of local anesthetic spread, and overall clinical effectiveness. This scoping review aimed to systematically map and synthesize the available evidence on aQLB and identify key knowledge gaps relevant to clinical practice and future research. METHODS: A comprehensive search of PubMed, Embase, Scopus, Web of Science, and the Cochrane Library was conducted from database inception to February 14, 2026. The search terms included variations of aQLB and related terminology. Only randomized controlled trials were included in this review. RESULTS: A total of 1174 records were identified, of which 360 underwent full-text assessment, and 119 randomized controlled trials were included. Most studies were conducted in Asia (63%) and involved adults (92%). Abdominal and urological procedures were the most commonly studied surgical indications (56%), followed by orthopedic surgeries (26%) and obstetric-gynecological procedures (17%). Multiple aQLB variants have been reported, including transmuscular, subcostal anterior, supra-arcuate ligament, and lateral arcuate ligament approaches. Comparators included sham or no block, wound infiltration, transversus abdominis plane block, erector spinae plane block, paravertebral block, neuraxial techniques, and other regional techniques. Across studies, the aQLB generally reduced postoperative pain scores, opioid consumption, and postoperative nausea and vomiting. However, the findings were heterogeneous and varied by surgical procedure and study design. CONCLUSIONS: The available literature suggests that aQLB may provide effective postoperative analgesia and opioid-sparing benefits across different surgical procedures. However, inconsistent findings among studies, the limited number of well-designed randomized controlled trials, and substantial heterogeneity across surgical populations restrict the strength of the current conclusions. Moreover, the deep anatomical location of the block, technical complexity, and potential risks should be considered when evaluating its role in routine clinical practice.