Preoperative CT findings predict the development of metachronous contralateral inguinal hernia after unilateral inguinal hernia repair: a single-center retrospective cohort study.

Purpose: To identify potential clinical and preoperative CT risk factors that can predict the development of metachronous contralateral inguinal hernia (MCIH) after unilateral inguinal hernia repair (IHR).

Methods: This study included unilateral inguinal hernia patients seen from 2016 to 2019 who underwent CT and subsequent IHR and had at least five years of follow-up. Preoperative CT scans were retrospectively reviewed for the presence of asymmetric spermatic cord fat and weakness of the transversalis fascia. The correlations of each CT feature and other clinical characteristics with the development of MCIH were calculated. The Kaplan-Meier model and multiple logistic regression were used to evaluate the associations among CT features, clinical variables and MCIH.

Results: A total of 677 male patients aged > 40 years were included in the study cohort. After more than 5 years of follow-up, 162 patients developed MCIH, representing an incidence of 23.9%. Patients with radical prostatectomy or peritoneal dialysis [P < 0.0001, HR 4.189 (95% CI 2.369 to 7.406)], primary left-sided IHR [P = 0.0032, HR 1.626 (95% CI 1.177 to 2.244)], and direct, femoral or pantaloon hernias were predisposed to MCIH. Asymmetric spermatic cord fat [P = 0.0002, HR 1.203 (95% CI 0.8785 to 1.648)] and weakness of the transversalis fascia [P < 0.0001, HR 7.914 (95% CI 5.666 to 11.05)] on preoperative CT were also identified as risk facts and demonstrated to be independent predictive factors for MCIH development.

Conclusion: Asymmetric spermatic cord fat and weakness of the transversalis fascia were predictive factors for MCIH development. For decision making regarding prophylactic contralateral IHR at the time of index surgery, preoperative CT findings as well as clinical characteristics should be considered.