Comparison of TAP Block and Umbilical Paramedian Linea Semilunaris Block in Pediatric Laparoscopic Surgery

Effective postoperative pain management is an important component of perioperative care in pediatric patients. Inadequately controlled postoperative pain may result in agitation, delayed mobilization, delayed oral intake, prolonged hospitalization, and increased analgesic requirements. Although opioids are commonly used for postoperative analgesia, their use in pediatric patients may be associated with adverse effects such as nausea, vomiting, sedation, respiratory depression, and delayed recovery. Therefore, opioid-sparing multimodal analgesic strategies, including ultrasound-guided regional anesthesia techniques, have become increasingly important in pediatric perioperative care.

The transversus abdominis plane (TAP) block is one of the commonly used abdominal wall blocks in pediatric abdominal surgery. However, its dermatomal distribution may be variable, and adequate analgesia may require bilateral or multiple injections. The linea semilunaris block is a more recently described fascial plane block targeting the anatomical region where the internal oblique and transversus abdominis muscles converge. This approach may allow wider local anesthetic spread and potentially provide effective analgesia for both the lateral abdominal wall and regions closer to the midline. However, clinical evidence regarding the linea semilunaris block remains limited, particularly in pediatric patients.

This prospective, randomized controlled trial will include 56 pediatric patients undergoing elective laparoscopic abdominal surgery. After written informed consent is obtained from a parent or legal guardian, participants will be randomly assigned in a 1:1 ratio using a computer-generated randomization sequence and sequentially numbered, sealed, opaque envelopes.

Following induction of general anesthesia and before the start of surgery, participants will receive one of two ultrasound-guided regional anesthesia techniques. Participants assigned to the linea semilunaris block group will receive an ultrasound-guided linea semilunaris block, whereas participants assigned to the TAP block group will receive an ultrasound-guided transversus abdominis plane block. In both groups, 0.2% bupivacaine will be administered at a volume of 0.5 mL/kg, with the total bupivacaine dose limited to 2 mg/kg. All block procedures will be performed by anesthesiologists experienced in pediatric ultrasound-guided regional anesthesia.

All participants will receive standard general anesthesia and perioperative monitoring. Postoperative pain will be assessed using age-appropriate FLACC or Wong-Baker Faces pain scales at predefined postoperative time points.

The primary outcome of the study will be total opioid consumption during the first 24 hours after surgery. Secondary outcomes will include postoperative pain scores, time to first analgesic requirement, additional analgesic requirements, postoperative nausea and vomiting, and block-related complications. The study aims to determine whether the linea semilunaris block provides effective postoperative analgesia and reduces opioid requirements compared with the TAP block in pediatric laparoscopic abdominal surgery.

Inclusion criteria

• Patients scheduled for elective pediatric laparoscopic abdominal surgery
• Age within the specified eligibility range
• American Society of Anesthesiologists (ASA) physical status I or II
• Written informed consent provided by a parent or legal guardian
• Adequate ultrasound visualization for the planned regional block
• No known allergy to bupivacaine or ultrasound gel
• No coagulopathy
• No infection at the block injection site
• No previous surgery at the block injection site
• No anticipated requirement for postoperative intensive care unit admission

Exclusion criteria

• Refusal of the parent or legal guardian to participate
• Emergency surgery
• Inadequate ultrasound visualization
• Coagulopathy
• Infection or previous surgery at the block injection site
• Known allergy to bupivacaine or ultrasound gel
• Conversion from laparoscopic to open surgery
• Requirement for postoperative intensive care unit admission
• ASA physical status III or higher