Purpose: This study was done to identify risk factors for metachronous manifestation of contralateral inguinal hernia in patients with unilateral inguinal hernia.
Methods: Characteristics of 156 patients with metachronous contralateral hernia were compared with those of 156 patients with unilateral hernia who were ascertained not to have presented with contralateral hernia.
Results: There was a tendency for the hernia to be more often on the left side in 88 of 156 patients (56.4%) with contralateral manifestation compared with 70 of 156 patients (44.9%) in the control group (P =.054). The age at hernia repair of the patients with contralateral manifestation, 1 to 120 months (median, 14 months), was significantly younger than the 1 to 149 months (median, 20 months) of the control patients (P =.016). More patients with contralateral manifestation had a family history of inguinal hernia, and the percentage, 24.4%, was significantly higher than the 14.7% in the control group (P =.046). A univariate analysis with the Cox regression models found that hernia on the left side and a positive family history were significantly associated with the metachronous manifestation of contralateral hernia (hazard ratio [HR], 1.40; P =. 037 and HR, 1.59; P =.013, respectively).
Conclusion: The risk of metachronous manifestation of contralateral hernia is high in patients with left-side hernia and in those with a family history, and the incidence of contralateral hernia is at most 10% in these patients. The authors think that the incidence is still too low to justify routine exploration and surgery for a patent processus vaginalis. Contralateral exploration should therefore be reserved for high-risk patients in whom second anesthesia and surgery have to be avoided.