In routine pediatric surgical practice, lower abdominal surgeries are commonly performed. Inadequate control of postoperative pain can hinder functional recovery and may lead to negative behavioral changes as well as parental dissatisfaction. Regional anesthesia techniques are widely recommended for pain management in pediatric surgery, as they reduce the need for parenteral opioids and improve the effectiveness of postoperative pain control, patient comfort, and parental satisfaction.

Various nerve block techniques have been developed to enhance postoperative analgesia and facilitate recovery in pediatric patients. However, there is still no consensus regarding the most effective regional anesthesia strategy for pediatric surgical procedures.

Among regional anesthesia techniques used for pain management in children undergoing lower abdominal surgery, caudal block remains the most commonly applied method. The introduction of real-time ultrasound guidance has improved the reliability and safety of caudal blocks. Nevertheless, a major limitation of this technique is its relatively short duration of action following a single injection, even when long-acting local anesthetics or adjuvant agents are used. Consequently, several fascial plane blocks, such as the quadratus lumborum block, transversus abdominis plane block, and rectus sheath block, have been proposed as alternative approaches for postoperative analgesia in children.

The erector spinae plane block is a regional anesthesia technique that has been applied at thoracic, lumbar, cervical, and sacral levels for both acute and chronic pain management. By providing blockade of both somatic and visceral pain pathways, it has demonstrated effective postoperative analgesic properties in a variety of thoracic and abdominal surgical procedures. The technique involves the injection of a local anesthetic into the interfascial plane between the erector spinae muscle and the transverse process, allowing longitudinal spread of the anesthetic across multiple spinal levels.

With a growing body of evidence supporting its feasibility and effectiveness, the erector spinae plane block has gained increasing attention in pediatric anesthesia practice.

The aim of this study is to evaluate and compare the analgesic efficacy and safety of ultrasound-guided erector spinae plane block and caudal block in pediatric patients undergoing unilateral lower abdominal surgery under general anesthesia. The primary objective is to compare postoperative pain levels between the two techniques using the FLACC score, which assesses facial expression, leg position, activity, crying, and consolability. Secondary objectives include the evaluation of intraoperative heart rate, blood pressure, and oxygen saturation, block application times, parental satisfaction, and the incidence of postoperative side effects.

Inclusion Criteria:

Children aged 1 to 8 years

Scheduled for elective lower abdominal surgery

American Society of Anesthesiologists (ASA) physical status I-II

Written informed consent obtained from parent(s) or legal guardian(s)

Exclusion Criteria:

Presence of anatomical abnormalities

Coagulation disorders

Infection at the site of block application

Severe cardiovascular, neurological, respiratory, or metabolic disease

Known allergy to study medications

Failed regional block

Bilateral surgery or additional surgical procedures involving different surgical sites

Refusal of parent(s) or legal guardian(s) to provide consent