The relationship between contralateral patent processus vaginalis and metachronous contralateral inguinal hernia in children with unilateral inguinal hernia: a prospective observational study.

Purpose: 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.

Method: 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.

Results: 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%.

Conclusion: 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.

Trial Registration: The Chinese Clinical Trial Registry ( www.chictr.org.cn ), number ChiCTR2000041307.