We previously conducted several studies to evaluate factors of urinary incontinence after robot-assisted radical prostatectomy (RARP) [ref.1, 2]. In this study, we further investigated uroflowmetry parameters with relevance to urinary incontinence and also analyzed the change between preoperative and postoperative values of uroflowmetry parameters in men undergoing RARP for prostate cancer.

From November 2011 to December 2018, a total of 428 patients received uroflowmetry tests before and after RARP for prostate cancer. Clinical data including age, prostate-specific antigen (PSA) before prostate biopsy, preoperative prostate volume, body mass index (BMI), uroflowmetry parameters, and core lower urinary tract symptom scores (CLSS) were retrospectively collected from our medical records. Changes in uroflowmetry parameters were investigated and analyzed for association with the recovery of urinary continence.

Preoperative and postoperative clinical characteristics including UFM parameters are shown in Table1. When preoperative and postoperative UFM parameters were compared, maximum flow rate (MFR) significantly increased postoperatively (14.4 mL/s vs. 17.1 mL/s, P<0.001). Voided volume (VV) and post-void residual urine (PVR) significantly decreased postoperatively (219 mL vs. 144 mL and 37 mL vs. 26 mL, respectively; both P<0.001). These findings reflect the results of waterfall charts of the change in each UFM parameter (Fig.1A-F). VV decreased in 72% of the patients (Fig.1A). In particular, patients with over 150 mL reduction accounted for 25% (Fig.1B). PVR decreased in 67% of the patients and MFR increased in 72% of the patients (Fig.1C-F). Kaplan-Meier curves showed that the group with a more amount of reduction in voided volume (over 150 mL reduction) had worse recovery of continence after RARP (Fig.1G).

The present findings showed that MFR increased significantly while VV and PVR  decreased significanly after RARP-procedure (Table1, Fig.1A-F). The changes in MFR and PVR may be explained by the mitigation of obstruction in the urethra due to the procedure of prostatectomy.  

We also found that the group with a more amount of reduction in voided volume (over 150 mL reduction) had worse recovery of continence after RARP (Fig.1G). Since the bladder neck is inevitably resected to a certain degree considering the nature of RARP-procedure, it may be not surprising to find that VV decreased after RARP. Were this to be the case, it may also be expected that PV may be a predictor of the reduction in VV, since a wider resection of the bladder neck may be necessary to resect a larger prostate. However, our findings did not show any pre-operative predictors including PV that contributed to the reduction in  VV.

Dramatic changes were observed in uroflowmetry results after RARP. To note, reduction in VV  was associated with a worsening of recovering urinary continence after RARP.

Yamada Y, Fujimura T, Fukuhara H, Sugihara T, Nakagawa T, Kume H, Igawa Y, Homma Y. Predictors of Early Continence after Robot-assisted Radical Prostatectomy. Low Urin Tract Symptoms. 2018; 10:287-291.
Yamada Y, Fujimura T, Fukuhara H, Sugihara T, Miyazaki H, Nakagawa T, Kume H, Igawa Y, Homma Y. Overactive bladder is a negative predictor of achieving continence after robot-assisted radical prostatectomy. Int J Urol. 2017; 24:749-756.
Haga N, Hata J, Matsuoka K, Koguchi T, Akaihata H, Kataoka M, Sato Y, Ogawa S, Ishibashi K, Kojima Y. The impact of nerve-sparing robot-assisted radical prostatectomy on lower urinary tract function: Prospective assessment of patient-reported outcomes and frequency volume charts. Neurourol Urodyn. 2018; 37:322-330.

Continence 7S1 (2023) 100872
DOI: 10.1016/j.cont.2023.100872