Metachronous contralateral inguinal hernia in neonates: incidence and risk factors from a 10-year single-center cohort

The management of the contralateral groin during neonatal inguinal hernia repair remains controversial. While selective approach is standard in older children, the high incidence of patent processus vaginalis (PPV) in neonates warrants reevaluation. This study aimed to determine the incidence of and risk factors for metachronous contralateral inguinal hernia (MCIH) in neonates. This retrospective cohort study included neonates (≤ 44 weeks post-menstrual age) undergoing unilateral inguinal hernia repair (2013–2022). Exclusion criteria included bilateral hernias or planned bilateral exploration. Primary outcome was discovering the MCIH incidence ( which is clinically diagnosed contralateral hernia that requiring surgical repair). Of 415 neonates undergoing hernia repair, 312 met inclusion criteria. Median follow-up was 4.2 years (IQR: 2.1–6.8). Forty-eight patients (15.4%) developed MCIH at median 8.1 months postoperatively. Multivariate analysis identified independent risk factors: prematurity (< 37 weeks, OR 3.1, 95% CI 1.6–5.9, p < 0.001), left-sided initial hernia (OR 2.8, 95% CI 1.4–5.4, p = 0.003), and ventriculo-peritoneal shunt (OR 4.5, 95% CI 1.2–16.8, p = 0.025). Subgroup analysis revealed MCIH rates of 28.6% in preterm infants, 25.4% after left-sided repair, and 41.7% with VP shunts. No major complications occurred from initial repairs. Neonates, particularly those who are premature, present with left-sided hernia, or have VP shunts, face substantially elevated MCIH risk. These data suggest that risk-stratified approach incorporating contralateral diagnostic laparoscopy may help guide decision-making regarding the use of contralateral diagnostic laparoscopy in high-risk neonates while minimizing unnecessary exploration.