This prospective randomized controlled clinical trial aims to compare the analgesic effectiveness of the Erector Spinae Plane (ESP) block and the Quadratus Lumborum (QL) block in pediatric patients undergoing appendectomy. Both regional anesthesia techniques have been shown to reduce opioid requirements and improve postoperative recovery in children; however, there is limited evidence directly comparing their efficacy. In this study, eligible participants will be randomly assigned to receive either an ESP or a QL block in addition to standard general anesthesia before surgical incision. Postoperative outcomes will include pain scores, total opioid consumption, time to first analgesic requirement, mobilization time, parental satisfaction, length of hospital stay, block-related complications and block performance time. The findings are expected to guide clinicians in selecting the most effective regional anesthesia technique for postoperative pain control in pediatric appendectomy.

Appendectomy is one of the most common emergency surgical procedures in children, and effective postoperative analgesia plays a key role in patient comfort, early mobilization, and reduced opioid exposure. Regional anesthesia techniques have gained increasing importance in pediatric anesthesia due to their opioid-sparing effect and favorable safety profile. Among these techniques, the Erector Spinae Plane (ESP) block and the Quadratus Lumborum (QL) block have shown promising results; however, there is a lack of high-quality randomized controlled trials directly comparing their clinical efficacy in pediatric appendectomy.

This study will prospectively enroll pediatric patients between 3 and 13 years of age who are scheduled to undergo appendectomy. After obtaining informed parental consent, participants will be randomly allocated to either the ESP block group or the QL block group. All blocks will be performed under ultrasound guidance using 0.25% bupivacaine at a dose of 0.5 mL/kg following the induction of general anesthesia. Standardized postoperative analgesia protocols will be applied to all participants.

Pain scores will be measured at predefined time points using a validated pediatric pain scale. Secondary outcomes will include total opioid consumption during the first 24 hours, the time to first rescue analgesic requirement, mobilization time, length of hospital stay, parental satisfaction scores, and any block-related complications. Patient data will be collected by trained investigators who will be blinded to group allocation.

The goal of this trial is to determine whether ESP or QL block provides superior postoperative pain control and recovery in pediatric appendectomy. The results may contribute to evidence-based recommendations for regional anesthesia selection in pediatric surgical practice.

Inclusion Criteria:

• Patients aged 3-13 years
• Diagnosis of acute appendicitis requiring appendectomy
• ASA physical status I-II
• Planned general anesthesia with intraoperative regional block (ESP or QL block)
• Written informed consent obtained from parents or legal guardians

Exclusion Criteria:

• Refusal of regional block by family or anesthesia team
• Coagulopathy or anticoagulant medication use
• Local infection at the block injection site
• Known allergy or contraindication to local anesthetics
• Neurological or neuromuscular disorders
• Cognitive impairment preventing postoperative pain assessment
• Conversion to open surgery
• Intraoperative complications requiring deviation from study protocol

The sharing of IPD is permitted under the condition that the organisation requesting its sharing provides a valid reason.