Laterality and Embryologic Basis of Pediatric Inguinal Hernias

Epidemiology

More than 90 % of pediatric inguinal hernias occur in male children, reflecting the influence of testicular descent on the persistence of a patent processus vaginalis. 1
A patent processus vaginalis (PPV) is identified in up to 80 % of term male infants; prevalence declines with age to about 64 % in infants younger than 2 months, 33–50 % in children younger than 1 year, and roughly 15 % by age five years. 1

Testicular descent proceeds in two phases: an intra‑abdominal phase (approximately 8–15 weeks gestation) and an extra‑abdominal phase (approximately 25–35 weeks gestation). 2
The right testis typically descends later than the left, extending the period during which the processus vaginalis remains patent on the right side. 2
During descent, the testis drags a peritoneal extension that forms the processus vaginalis, creating a potential conduit for herniation. 2

Failure of obliteration of the processus vaginalis results in a persistent patent processus vaginalis (PPV), which constitutes the anatomical substrate for all indirect inguinal hernias in children. 3

Laparoscopic exploration of the contralateral groin in children with a unilateral hernia reveals a PPV in approximately 15 % of five‑year‑old patients, supporting routine contralateral assessment in selected cases. 3