Age-related probability of contralateral processus vaginalis patency in children with unilateral inguinal hernia

Contralateral groin exploration with closure of a patent processus vaginalis (PPV) in children with a unilateral inguinal hernia remains controversial. We aimed to generate precise, age-related probabilities of patency of the contralateral processus vaginalis (PV) in infants with a unilateral inguinal hernia to guide practice. Retrospective review of all unilateral laparoscopic inguinal hernia repairs in 5 years to determine patency of contralateral PV. Using logistic binomial regression, age-adjusted odds ratio (OR), probability of contralateral PPV and number needed to explore (NNE) in order to close all PPVs were estimated. Data from 331 children [262 male, median 3.8 months corrected gestational age (CGA)] were analysed; 160 (48 %) had a contralateral PPV. In the regression model, CGA is linearly related to log[OR] such that for each month increase in CGA, the log[OR] of having a contralateral PPV decreased by 0.017 +/- A 0.006 (mean +/- A SEM; p = 0.005). Gender and side of hernia had no significant effect. The probability of contralateral PPV is 50 % (NNE = 2) at 8 m CGA, 33 % (NNE = 3) at 49 m and 25 % (NNE = 4) at 72 m. These data contribute to our knowledge of the natural history of the PV and may help guide the need for contralateral groin exploration in infants with inguinal hernia.