Incidence and risk factors of inguinal hernia after robot-assisted radical prostatectomy: a retrospective multicenter cohort study in Japan (the MSUG94 group)

To investigate the incidence and risk factors of inguinal hernia (IH) after robot-assisted radical prostatectomy (RARP) using a multicentric database. The present study used a multicentric database (the MSUG94) containing data on 3,195 Japanese patients undergoing RARP between 2012 and 2021. Surgical procedures utilized for IH prevention were as follows: isolation of the vas deferens, transection of the vas deferens, isolation of the spermatic vessels, and separation of the peritoneum from the internal inguinal ring. The primary and secondary endpoints were IH-free survival and any association between post-RARP IH and clinical covariates. The prophylactic effect of the above procedures were also assessed. IH prevention was attempted in 1,465 (46.4%) patients at five of the nine hospitals. During follow-up (median 24 months), post-RARP IH developed in 243 patients. The post-RARP IH-free survival rates at years 1, 2, and 3 were 94.3%, 91.7%, and 90.5%, respectively. Old age (hazard ratio [HR] 1.037; 95% confidence interval [CI] 1.014–1.061; p = 0.001), low BMI (HR 0.904; 95% CI 0.863–0.946: p < 0.001), and low hospital volume (HR 1.385; 95% CI 1.003–1.902; p = 0.048) were independently associated with IH development. None of the procedures for IH prevention were associated with IH development. Our findings may represent the current, real-world status of post-RARP IH in Japan. The prophylactic effects of the surgical procedures for IH prevention should be further investigated in well-designed, prospective studies to optimize the surgical technique.