Efficacy of quadratus lumborum block in the treatment of acute and chronic pain after cesarean section: A systematic review and meta-analysis based on randomized controlled trials

Background: This analysis aimed to explore the analgesic effects of quadratus lumborum block on acute and chronic postoperative pain among patients undergoing cesarean section. Methods: PubMed, Cochrane, Embase, Web of Science, China National Knowledge Infrastructure, Wanfang, and VIP databases for Randomized Controlled Trials (RCTs) that focused on the use of quadratus lumborum block in cesarean section procedures were searched from the inception of the databases until December 2022. Studies were screened based on inclusion and exclusion criteria, and were then conducted for quality assessment and data extraction. Meta-analysis was performed using Stata 15.0 software. Two researchers independently screened the studies, extracted data, and evaluated the risk of bias for the included studies. In case of any disagreements, it was resolved by consultation with a third party opinion. Results: A total of 21 studies involving 1976 patients were finally included, with an overall acceptable study quality level. Compared to the control group, the administration of Quadratus Lumborum Block (QLB) resulted in significant reduction in the postoperative 24-hour visual analog scale (VAS) score (WMD = -0.69, 95% CI: -1.03 similar to -0.35, P < .001) and the consumption of opioid analgesics within 24 hours after surgery (WMD = -2.04, 95% CI: -2.15 similar to -1.92, P = .002). The incidence of chronic pain 3 months QLB (OR = 0.41, 95% CI: 0.09 similar to 1.88, P = .253) and 6 months (OR = 0.83, 95% CI: 0.33 similar to 2.07, P = .686) after surgery were observed to increase as compared with the control group. Conclusions: The use of QLB for postoperative analgesia after cesarean section, particularly in the relief of acute postoperative pain, had been proven to significantly decrease the VAS score and morphine consumption within the first 24 hours after surgery. However, further studies are needed to determine its impact on managing chronic postoperative pain.