Evaluation of Skin-to-Epidural Distance at Different Vertebral Levels by Ultrasonography in Infants: A Prospective Observational Study

The goal of this observational study is to learn about the distance between the skin and the epidural space in infants younger than 12 months. The epidural space is an area near the spinal cord where doctors can give pain medicine to help control pain during and after surgery. Epidural pain treatment can greatly reduce the amount of pain a child feels after surgery. Researchers will use ultrasound, a method that uses sound waves to create images inside the body and does not have harmful effects on the body, to measure this distance in babies having planned surgery under general anesthesia. General anesthesia is a medicine that keeps patients asleep during surgery. The main questions this study aims to answer are: Does the distance between the skin and the epidural space change with a baby's age, weight, height, or gestational age? Are the measurements similar when ultrasound images are taken from different directions? How close are the ultrasound measurements to the actual depth reached by the needle in babies who receive epidural pain treatment as part of their regular medical care? Participants will have ultrasound images taken after they are asleep under general anesthesia. Measurements will be taken at 4 different areas of the lower back and from 2 different viewing directions. The measurements will be performed by 2 experienced doctors. Each doctor will repeat the same measurements 2 times to check consistency. Participants will receive epidural pain treatment only if it is already planned as part of their usual care. No extra invasive procedure or additional medication will be given for this study.

Inclusion Criteria: * Infants aged 0 to 12 months * Scheduled for elective surgery under general anesthesia * American Society of Anesthesiologists physical status I to III * Written informed consent obtained from parents or legal guardians Exclusion Criteria: * Known vertebral or spinal cord anomalies, including scoliosis or spina bifida * Previous spinal surgery * Neuromuscular disease or known spinal cord pathology * Congenital syndromes associated with systemic malformations * Severe pulmonary, cardiac, hemodynamic, or neurological instability * Emergency surgery * Unreliable or incomplete ultrasonographic measurement data due to technical difficulties * Absence of written informed consent from parents or legal guardians