Analgesic effects of ultrasound-guided preoperative posterior Quadratus Lumborum block in laparoscopic hepatectomy: A prospective double-blinded randomized controlled trial

To determine if single-injection bilateral posterior quadratus lumborum block (QLB) with ropivacaine would improve postoperative analgesia in the first 24 h after laparoscopic hepatectomy, compared with 0.9% saline.