BACKGROUND: Ultrasound?guided quadratus lumborum block (QLB) is a regional anesthetic technique which can provide post-op pain control for pediatric patients undergoing abdominal surgery. We hypothesized that the quadratus lumborum block would be as efficacious as a caudal block in providing pain control.

OBJECTIVE: To compare the postoperative analgesic effect of ultrasound-guided QLB versus ultrasound-guided caudal block among 1-6 years old children undergoing lower abdominal and urological surgeries in Philippine Children's Medical Center.

METHODS: This is a single-blinded randomized control trial. 50 patients enrolled aged between 1 and 6 years. The patients were randomly classified into the caudal block group and quadratus lumborum block group. The primary outcome is the need for analgesia during the first 24 hours.

RESULTS: A significant difference in the proportion of patients who requested for rescue analgesia was observed with caudal block having more patients in need of analgesic (100% CB vs 48% QLB, p<0.001). No postoperative complication was observed.

CONCLUSIONS AND RECOMMENDATIONS: The quadratus lumborum block was more effective in reducing the postoperative pain management during the initial 48 hours. Quadratus lumborum block is recommended for future pediatric procedures requiring postoperative pain control, safety, practicality and economy.