Prospective evaluation of an intraoperative urodynamic stress test predicting urinary incontinence after robot-assisted laparoscopic radical prostatectomy.

Introduction: Multiple factors influence postprostatectomy incontinence (PPI). This study evaluates the association between an intraoperative urodynamic stress test (IST) with PPI.

Materials and methods: This is an observational, single-center, prospective evaluation of 109 robot-assisted laparoscopic radical prostatectomies (RALPs) performed between July 2020 and March 2021. All patients underwent an intraoperative urodynamic stress test (IST) in which the bladder is filled up to an intravesical pressure of 40 cm H₂O to evaluate whether the rhabdomyosphincter is capable of withstanding the pressure and ensure continence. Early PPI was evaluated using a standardized 1-h pad test performed the day after removal of the urinary catheter. The association of IST and PPI was evaluated using univariate and multivariable logistic regression models.

Results: Nearly 76.6% of the patients showed no urine loss during the IST ("sufficient" population group). There was no significant correlation between this group and PPI after catheter removal (P = 0.5). Subgroup analyses of the "sufficient" patient population showed a 3.1 higher risk of PPI when no nerve sparing was performed (95% confidence interval: 1.05-9.70, P = 0.045).

Conclusion: A sufficient IST, as a surrogate variable for a fully obtained rhabdomyosphincter, has no significant predictive value on its own but seems to be the optimal prerequisite for continence, since the data shows that the lack of neurovascular supply required for a functioning sphincter leads up to a 3.1 times higher risk for PPI.