To evaluate anatomical factors associated with early recovery of urinary continence after RARP including pre-operative membranous urethral length (MUL), gland weight, index tumour volume and nerve-sparing status.

We performed a retrospective analysis of patients from a prospectively collected database who underwent RARP between January 2017 and September 2019. All patients who underwent pre biopsy multiparametric magnetic resonance imaging (mpMRI) of the prostate were identified and included in the study. Patient’s pre-operative clinicodemographic data and anatomical variables such as pre-operative MUL, gland weight, index tumour volume and nerve-sparing status were collected. Urinary continence was evaluated at 6 weeks, 3 months and 6 months post-operatively using the EPIC questionnaire (1). Continence was defined as no pad usage or one safety pad with pad weight of <20g/24 hours.

A total of 77 patients with pre-operative mpMRI underwent RARP during the study period. Continence was achieved in 14 (18.2%), 17 (22.1%), 31 (40.3%) at 6 weeks, 3 months and 6 months, respectively. On univariate analysis, smaller index tumour volume significantly influences continence at 3 months (4.2 vs 1.4mls, p=0.037). The risk of incontinence in patients with MUL of <10mm, 10-15mm and >15mm at 6 months was 57.1%, 48.3% and 40.9%.  Multivariate analysis identified gland weight of <40g is an independent factor associated with continence at 6 weeks (p=0.048), 3 months (p=0.044) and 6 months (p=0.025). Patients with gland weight of >40g had a positive correlation with greater pad number at 6 months (p=0.006). The MUL did not significantly differ between the continent and incontinent groups at 6 weeks (median MUL 13.5 vs 13.7mm, p=0.879), 3 months (13.7 vs 13.7mm, p=0.987) and 6 months (13.3 vs 13.8mm, p=0.651). However, MUL had a significant negative correlation with pad number (p=0.034) and pad weight (p=0.004) at 6 weeks and pad number (p=0.025) at 6 months. Nerve-sparing was performed on 51 (66.2%) patients and 76.5% had bilateral nerve-sparing. Nerve-sparing status did not influence continence at 6 weeks (p=0.2), 3 months (p=0.225) and 6 months (p=0.57).

A successful radical prostatectomy requires oncologic control whilst simultaneously fulfilling the functional outcome of continence and potency. In particular, urinary incontinence is a well-recognised complication that can significantly impact an individual patient's quality of life. Anatomical factors such as prostate size, MUL and nerve-sparing status have been identified to affect urinary continence at >12 months after RARP2,3. The current study aimed to examine these factors and their impact on early recovery of urinary continence. Our results indicate a smaller index tumour volume and prostate volume (<40g) significantly impact the recovery of continence as early as 6 weeks following RARP. Although MUL and nerve-sparing status did not significantly determine continence status, shorter MUL was correlated with a greater number of pad use and pad weight at 6 weeks. These anatomical factors can be determined based on preoperative mpMRI and can be utilised to develop a preoperative risk assessment tool. This will allow clinicians to provide tailored preoperative counselling and optimise individual patient’s postoperative management after RARP.

A smaller index tumour volume and gland weight significantly influences the early recovery of urinary continence after RARP. The MUL and nerve-sparing status did not significantly impact a patient's recovery of urinary continence within 6 months after RARP. However, the risk of incontinence is higher in patients with shorter MUL and shorter MUL had a significant correlation with a higher number of pad use and pad weight at 6 weeks. Further analysis with a larger cohort is required to validate these findings.

Wei JT, Dunn RL, Litwin MS, Sandlier HM, Sanda MG. Development and validation of the expanded prostate cancer index composite (EPIC) for comprehensive assessment of health-related quality of life in men with prostate cancer. Urology. 2000; 56(6):899.
Labanaris AP, Zugor V, Witt JH. Robot-assisted radical prostatectomy in patients with a pathologic prostate specimen weight = 100 grams versus =50 grams: surgical, oncologic and short-term functional outcomes. Urol Int. 2013;90:24-30.
Kim LHC, Patel A, Kinsella N, Sharabiani MTA, Ap Dafydd DA, Cahill D (in press). Association between preoperative magnetic resonance imaging-based urethral parameters and continence recovery following robot-assisted radical prostatectomy. Eur Urol Focus. 2019; doi:10.1016/j.euf.2019.01.011.