Incidence of contralateral inguinal hernia: a prospective analysis.

Background/purpose: Contralateral groin exploration in children with unilateral inguinal hernia is still controversial, particularly in infants. The authors have attempted to determine the age- and gender-stratified incidence of contralateral hernia and the necessity of routine bilateral procedures.
Methods: This is a prospective study of 656 patients during a 34-month period at a single institution. Patients with unilateral hernia underwent an ipsilateral procedure only, regardless of age, gestational age, or gender. Follow-up was 6 to 40 months (mean, 25.5 months). Chi-square analysis was used for intergroup comparison (P < .05 significant).
Results: Of 656 children, 108 (16.5%) presented with synchronous bilateral hernias. Bilateral inguinal hernia was significantly more common in premature infants (28.0%) and young children (33.8% if <6 months, 27.4% if <2 years). Of the remaining 548, a metachronous contralateral hernia developed in 48 (8.8%) at a median interval of 6 months (range, 4 days to 7 years). This incidence was 13 of 105 (12.4%) in infants less than 6 months of age, 20 of 189 (10.6%) in children less than 2 years of age, 8 of 54 (14.8%) in premature infants, 6 of 81 (7.4%) in girls, and 8 of 29 (27.6%) in children with an incarcerated hernia. In the latter group, P < .05, chi2 analysis.
Conclusion: Routine contralateral inguinal exploration, without clinical evidence of a hernia, may be advisable in children with incarceration and possibly in premature infants. The low incidence of contralateral hernias in all other patients, regardless of gender or age, does not justify routine contralateral exploration.