OBJECTIVE: 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.
CONCLUSIONS: 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.

BACKGROUND: Patients undergoing unilateral inguinal hernia repair (IHR) are at risk of metachronous contralateral inguinal hernia (MCIH) development. We evaluated incidence and risk factors of MCIH development up to 25 years after unilateral IHR to determine possible indications for concomitant prophylactic surgery of the contralateral groin at the time of primary surgery.
METHODS: Patients between 18 and 70 years of age undergoing elective unilateral IHR in the University Hospital of Leuven from 1995 to 1999 were studied retrospectively using the electronic health records and prospectively via phone calls. Study aims were MCIH incidence and risk factor determination. Kaplan-Meier curves were constructed and univariable and multivariable Cox regressions were performed.
RESULTS: 758 patients were included (91% male, median age 53 years). Median follow-up time was 21.75 years. The incidence of operated MCIH after 5 years was 5.6%, after 15 years 16.1%, and after 25 years 24.7%. The incidence of both operated and non-operated MCIH after 5 years was 5.9%, after 15 years 16.7%, and after 25 years 29.0%. MCIH risk increased with older age and decreased in primary right-sided IHR and higher BMI at primary surgery.
CONCLUSIONS: The overall incidence of MCIH after 25-year follow-up is 29.0%. Potential risk factors for the development of a MCIH are primary left-sided inguinal hernia repair, lower BMI, and older age. When considering prophylactic repair, we suggest a patient-specific approach taking into account these risk factors, the surgical approach and the risk factors for chronic postoperative inguinal pain.

Inguinal hernia repair is a common operation performed in children. In Australia, open repair (OR) continues to be the preferred method of treatment in infants, despite laparoscopic repair (LR) gaining popularity amongst some international centres. Our aim was to analyse initial outcomes with LR at our paediatric centre.
We conducted a retrospective review of all patients <1 year of age who received LR or OR between January 2017 and July 2021 at our institution. Data were retrieved from both electronic and scanned medical records. Data were analysed using an unpaired t-test, Mann-Whitney test, Fisher\'s exact test or simple linear regression. A P-value <0.05 was considered significant.
A total of 376 patients were identified: LR was performed in 73 patients, and OR in 303 patients. Bilateral repair was more common amongst patients receiving LR: 56.2% versus 21.5%, P = 0.0001, treating either a symptomatic hernia or an intra-operative contralateral inguinal defect (70%). All LR patients received general anaesthetic, compared to 82.8% of patients in the OR group, P = 0.0001. There were no recurrences following LR and 3 with OR (P = 1.0). The metachronous contralateral inguinal hernia rate following OR was 10% (21/206). There was no significant difference in other complications, including wound infection, haematoma, testicular atrophy, and hydrocele formation.
In our population OR was performed more often than LR. Operative complication rates were equivalent between OR and LR groups. However, infants that underwent OR were significantly more likely to develop a MCIH.

Laparoscopic contralateral patent processus vaginalis (CPPV) repair in children is debatable due to the high CPPV rate, but low metachronous contralateral inguinal hernia (MCIH) rate. We conducted this study to find risk factors for MCIH.
We conducted a prospective, observational trial with patients recruited from Shanghai Children\'s Hospital. Eligible participants were patients under 16 years old with unilateral inguinal hernia whose parents did not opt for simultaneous CPPV repair. The subjects were followed for 24 to 34.1 months. Patients who developed MCIH were analyzed to identify the relationship between CPPV and MCIH.
Between October 17, 2018, and July 31, 2019, we included 184 patients and 182 completed follow-up. MCIH occurred in ten patients, of which 7 (7.53%) had CPPV and three (3.37%) had no CPPV. Univariate analysis showed that age (p = 0.025, OR = 0.938) and CPPV diameter (p = 0.003, OR = 1.783) were related to the development of MCIH. In multivariate analysis, only diameter of CPPV (p = 0.008, OR = 1.411) was associated with MCIH. The receiver operating characteristic (ROC) curve was used to test, and it was found that when the diameter of CPPV was greater than 4 mm, the Youden index was the highest, with a specificity of 62.8% and a sensitivity of 100%.
The incidence of MCIH was not statistically higher in patients with CPPV compared with those without CPPV, so there is no indication for routine CPPV repair. The risk of MCIH development increases with CPPV diameter. 4 mm is the optimal cutoff point. Large CPPVs (> 4 mm) could be treated to prevent future hernias.
The Chinese Clinical Trial Registry ( www.chictr.org.cn ), number ChiCTR2000041307.

OBJECTIVE: We use the laparoscopic percutaneous extraperitoneal closure (LPEC) method as the standard procedure for pediatric inguinal hernia. Despite judging there to be no contralateral patent processus vaginalis (PPV) at the time of the first LPEC, we experienced five cases in which metachronous contralateral inguinal hernia (MCH) developed, so we report the characteristics, including the predictors.
METHODS: For pediatric inguinal hernia, the LPEC method was used in 1277 cases from 2005 to 2019 in our department. Of these, 374 patients underwent unilateral LPEC, and we compared the 5 patients with MCH onset and the 369 without MCH onset. The items to be examined were the gender, age, presence of a low birth weight, initial-onset side, and contralateral internal inguinal ring classification.
RESULTS: There was no significant difference in the gender, age, initial-onset side, or contralateral internal inguinal ring classification between the two groups. Low-birth-weight infants were significantly more common among those with MCH than among those without MCH.
CONCLUSIONS: The only predictor of a contralateral onset after LPEC for pediatric inguinal hernia was a low birth weight. Therefore, for the above-mentioned unilateral LPEC cases, the possibility of a contralateral onset after LPEC due to acquired factors rather than congenital factors should be considered.