Extracorporeal Knot Placement in PIRS as a Potential Contributor to Postoperative Inguinal Pain: Anatomical and Histological Evidence

Background Percutaneous internal ring suturing (PIRS) is a widely used minimally invasive technique for pediatric inguinal hernia repair. However, postoperative inguinal pain (PIP) following PIRS remains incompletely understood. We hypothesized that extracorporeal knot placement within fascia–muscular layers, which contain abundant sensory nerve fibers, may contribute to postoperative pain following PIRS. Methods Thirty hernia sac specimens from children undergoing OH were examined histologically using H&E, anti-S100, and anti-PGP9.5 staining. For anatomical comparison, twelve full-thickness inguinal abdominal wall samples from six Green Island pigs were processed similarly. Results No nerve fibers were identified in human hernia sac specimens. Porcine abdominal wall samples contained abundant nerve fibers within subcutaneous, fascial, and muscular layers, but none in the peritoneum. Conclusion Fascia and muscle tissues are richly innervated, whereas the inguinal hernia sac lacks neural structures. Our findings support the hypothesis that extracorporeal knot placement within fascia-muscular layers may represent one contributing mechanism of postoperative inguinal pain following PIRS.