Participants will receive ultrasound-guided external oblique intercostal (EOI) fascial plane block at the end of surgery. Under general anesthesia, a linear ultrasound probe (6-13 MHz) will be placed transversely at the 8th-9th intercostal space along the anterior axillary line. A 22-gauge, 50-80 mm needle will be advanced in-plane into the fascial plane between the external oblique and intercostal muscles, and 0.2% ropivacaine 0.5 mL/kg (maximum 30 mL) will be injected. Postoperative pain management will include intravenous patient-controlled analgesia (IV-PCA) with fentanyl.

Participants will not receive the EOI block. All other perioperative management, including general anesthesia and postoperative intravenous patient-controlled analgesia (IV-PCA) with fentanyl, will be identical to the experimental group.

Under general anesthesia, a linear ultrasound probe (6-13 MHz) is placed transversely at the 8th-9th intercostal space along the anterior axillary line. A 22-gauge, 50-80 mm needle is advanced in-plane into the fascial plane between the external oblique and intercostal muscles. After confirming correct needle placement, 0.2% ropivacaine 0.5 mL/kg (maximum 30 mL) is injected. The procedure is performed at the end of otoplasty with rib cartilage graft to provide postoperative analgesia.

Total amount of opioid analgesic (fentanyl) administered via intravenous patient-controlled analgesia (IV-PCA) and additional rescue doses within 24 hours postoperatively. The total dose will be normalized to body weight (µg/kg).

Pain intensity at rest assessed using the Numerical Rating Scale (NRS, 0-10; higher scores = worse pain)