The relative position of ilioinguinal and iliohypogastric nerves in different age groups of pediatric patients

Background Ilioinguinal nerve (IIN) and iliohypogastric nerve (IHN) blocks provide good perioperative pain relief for children undergoing inguinal procedures such as inguinal hernia repair, orchiopexy, and hydrocelectomy. The aim of this ultrasound imaging study is to compare the relative anatomical positions of IIN and IHN in different age groups of pediatrics. Methods Two-hundred children (aged 1-82 months, ASA I or II) undergoing day-case surgery were consecutively included in this study. Following the induction of general anesthesia, an ultrasonographic exam was performed using a high-frequency linear probe that was placed on an imaginary line connecting the anterior superior iliac spine (ASIS) to the umbilicus. Results There were significant differences in ASIS-IIN (distance from ASIS to IIN), ASIS-IHN (distance from the ASIS to the IHN), and IIN-IHN (distance between IIN and IHN) between the age groups: < 12 months (n=84), 12-36 months (n=80), and > 37 months (n=36). However, IIN-Peritoneum (distances from IIN to peritoneum), skin-IIN, and skin-IHN (depth of IIN and IHN relative to skin) were similar in three groups. ASIS-IIN and ASIS-IHN showed significantly positive correlations with age. Conclusions Age should be considered when placing a needle in landmark techniques for pediatric II/IH nerve blocks. However, needle depth should be confirmed by the fascial click due to the lack of predictable physiologic factors.