It has been postulated that increased age can have a negative impact on return of continence after prostatectomy, perhaps owing to higher incidences of pre-existing lower urinary tract symptoms, larger prostatic volumes at the time of prostatectomy, and/or age-related functional changes to the lower urinary tract. Karakiewicz et al. in a population-based study of 2415 men found that age was a significant predictor of continence outcomes after radical prostatectomy on univariate and multivariate analysis [6]. Stanford et al. found in a population-based cohort of 1291 that persistent incontinence >18 months after prostatectomy was significantly higher in men >75 years old versus younger men (13.8% vs. 0.7–3.6%; p = 0.03) [4], a finding confirmed in a recent large retrospective review of 2849 men which found on multivariate analysis that the likelihood of continence recovery significantly decreases with increased age [7]. In contrast, Kadono et al. failed to demonstrate age as a predictor of persistent incontinence at 1 year postprostatectomy on univariate and multivariate analysis of data from 111 patients [8]. In addition, Catalona and Basler found that age and continence recovery did not correlate in a series of 784 men treated with radical prostatectomy [9].

As with age, the evidence characterizing the impact of BMI on postprostatectomy incontinence is variable. In a recent large retrospective review of 2849 patients, Matsushita et al. noted that higher BMI was associated with decreased recovery of incontinence at 6 and 12 months postprostatectomy. [7] Wiltz et al. found in a prospective study of 945 men who underwent robotic-assisted radical prostatectomy (RARP) that urinary continence outcomes were significantly lower at 1 and 2 years after prostatectomy in men with BMIs >30 kg/m² [10], a finding supported in a study of 589 men which found that PPI was more prevalent in physically inactive, obese men (BMI >30 kg/m²) [11]. Conversely, Hsu et al. prospectively followed 1024 men postprostatectomy and failed to demonstrate a relationship between BMI and PPI. In a recent study, Kadono et al. also found that BMI is not a predictor of urinary incontinence on univariate and multivariate analysis [8].

Up to 50% of men with urinary incontinence are found to have some element of bladder dysfunction after prostatectomy, including decreased compliance and detrusor over-/underactivity [12–14], though many men will have pre-existing functional changes in the lower urinary tract prior to prostatectomy [15, 16]. The etiology of these observed functional changes in the lower urinary tract is likely multifactorial, including anatomic changes, devascularization, and denervation of the bladder [17]. Detrusor overactivity can result in postprostatectomy incontinence, though pure detrusor overactivity incontinence is relatively rare (3%) [14].

There is evidence that pre-existing LUTS negatively impact continence rates postprostatectomy. In a prospective study of 482 men, Wei et al. found that preoperative continence was a significant predictor of postoperative continence on multivariate analysis [18]. In a study of 106 men, Rodriguez et al. found that men with occasional leakage postprostatectomy (76 of 106 men) were older, had more urinary symptom (higher American Urological Association symptom and bother scores (AUAs)), and had larger prostates [19].

Preservation of membranous urethral length during radical prostatectomy has been demonstrated to significantly improve continence rates and shorten time to recovery of incontinence after radical prostatectomy [20]. Optimization of membranous urethral length during radical prostatectomy is likely influenced by prostate size as well as preoperative membranous urethral length. Paparel et al. retrospectively analyzed 64 men who had both pre- and post-radical prostatectomy MRI investigations assessing membranous urethral length [21]. The authors found that a longer pre- and postoperative membranous urethral length and a lower membranous urethral loss ratio were associated with superior continence outcomes (p < 0.01, p < 0.01, and p = 0.2, respectively). Nguyen et al. in a retrospective study of 274 patients investigated with MRI pre-radical prostatectomy found that a longer “functional urethral length” (external urethral sphincter length) correlated positively with continence recovery and negatively with time to achieving continence after surgery [22]. A recent analysis by Matsushita et al. evaluating 2849 men with preoperative MRI confirms these findings, demonstrating that the likelihood of continence recovery significantly increases with longer preoperative membranous urethral length [7]. In contrast, Borin et al. in a prospective study of 200 patients did not demonstrate a negative impact of shorter urethral length on time to continence recovery nor overall incontinence [23]. However, urethral stump length was not measured. The transection was done just distal to the prostatourethral junction in an effort to achieve a negative margin.

As a shorter membranous urethral length and the presence of pre-existing lower urinary tract symptoms have been implicated in PPI, the impact of prostate size (which can influence the two aforementioned variables) on PPI has been questioned. Konety et al. retrospectively evaluated 2097 men treated with RP that had been investigated with transrectal ultrasound before surgery [24]. The authors found that men with prostate volumes >50 cm³ had lower levels of continence up to 2 years after surgery and that prostatic volume was a predictor of urinary functional recovery after prostatectomy. However, continence rates equalized across all prostate sizes at 2 years follow-up. In a retrospective study of 355 consecutive patients undergoing RARP, Boczko et al. demonstrated a 6-month continence rate of 97% for patients with prostate sizes <75 g vs. 84% of patients with prostates >75 g (p < 0.05) [25]. On the contrary, in their study of 111 patients Kadono et al. failed to demonstrate an impact of prostate size on continence after RP. Further, a large retrospective study of 3067 men found that prostate size was not significantly associated with urinary incontinence (p = 0.08) [26].

Our understanding of the impact of TURP prior to radical prostatectomy on continence is limited at present and based on small studies with low levels of evidence. Palisaar et al. prospectively collected data on 1760 patients treated with radical prostatectomy and retrospectively matched 62 patients with a history of TURP to 62 controls who did not [27]. At 1-year follow-up, no difference in perioperative complication rates and functional outcomes, including continence, was observed between the two groups. In addition, Su et al. retrospectively analyzed data from 2693 patients treated with radical prostatectomy, of which 49 patients had a history of TURP [28]. TURP had an impact on positive surgical margin but did not significantly impact functional outcomes including urinary continence.

The urethral sphincter complex is composed of two distinct components; the smooth-muscled internal (lissosphincter) sphincter found at the bladder neck and the striated external (rhabdosphincter) sphincter surrounding the membranous urethra [29]. The striated muscle of the external sphincter extends from the proximal aspect of the bulbar urethra and inserts posteriorly into the perineal body, forming an omega-shaped structure over the lateral and anterior aspects of the membranous urethra [30]. Additionally, the external urethral sphincter can overlap the prostate, and striated muscle is incorporated into the prostatic apex [29, 31].

Both components of the urethral sphincter complex have been implicated in continence after prostatectomy. The internal urethral sphincter is responsible for passive continence at normal activity levels, and bladder neck preservation (and by extension, sparing of the internal sphincter) may result in earlier return of continence and improved overall continence rates. Stolzenburg et al. retrospectively analyzed 150 men treated with bladder neck sparing RP compared to 90 men who did not have a bladder neck sparing procedure [32]. The authors found that immediate postoperative continence and continence at 3 months after surgery were significantly better in the bladder neck sparing group and that bladder neck sparing had no impact on positive surgical margin status. A recent systematic review and meta-analysis by Ma et al. support these findings, demonstrating that bladder neck sparing during RP improved early recovery and overall long-term (1 year) continence rates as well as decreasing the incidence of vesicourethral anastomotic strictures without compromising oncologic outcomes [33].

Proper function of the external urethral sphincter depends on the presence of healthy striated muscle as well as the integrity of membranous urethral supporting structures. Skeldon et al. analyzed anatomical specimens in 61 patients treated with RP and devised a grading system that quantified the amount of striated muscle present in specimens isolated from the prostatic apex [34]. The authors found increased amounts of striated muscle in the specimens had a significant benefit on urinary incontinence. Tuygun et al. studied 36 patients after radical prostatectomy and demonstrated on MRI that external urethral sphincter fibrosis was present in 100% of patients with urinary incontinence versus 29% of those with no incontinence and that milder fibrosis was associated with a shorter duration of incontinence [35]. The authors concluded that fibrosis likely impacts urinary continence after radical prostatectomy by negatively impacting external sphincter function.

Regarding the type of RP, open versus laparoscopic versus robotic-assisted, one randomized comparison of laparoscopic RP with and without robotic assistance did not show a significant difference in urinary continence [36]. Although there has been more recent demonstration of statistically significantly superior continence outcomes with robotic-assisted RP compared to open RP [37–40], a recently published RCT from Australia showed no difference in early continence outcomes between open and robotic-assisted RP [41].

Membranous urethral supporting structures can be divided into pelvic floor, anterior, and posterior supporting components. The pelvic floor consists of the levator ani muscles with associated fascia. The levator ani muscles surround the external urethral sphincter circumferentially and, however, are separated from the sphincter complex by a distinct layer of connective tissue [42]. The pelvic floor likely assists the continence mechanism by providing additional occlusive forces to the urethra during an increase in intra-abdominal pressures [43]. Anterior support structures include the puboprostatic ligament, the pubovesical ligament, and the tendinous arch of the pelvic fascia. Together, they attach the membranous urethra to the pubic bone and stabilize the position of the external urethral sphincter/bladder neck [44]. Denonvilliers fascia, the rectourethralis muscle, and the perineal body support the membranous urethra posteriorly [42, 45].

Studies have demonstrated that preservation or reconstruction of these circumferential supporting structures improves postprostatectomy incontinence. Stolzenburg et al. prospectively analyzed 50 men treated with nerve and puboprostatic ligament sparing RP and compared them to 50 men treated with nerve sparing radical prostatectomy alone [46]. The authors found that early recovery of continence (<3 months) was significantly improved in men treated with the puboprostatic ligament sparing procedure (chi-square test, p = 0.03). Reconstruction of the posterior musculofascial plate (Denonvillers fascia) with the so-called Rocco stitch has also been demonstrated in numerous studies to improve continence. Rocco et al. compared 250 patients treated with posterior reconstruction to a historical cohort of 50 patients who did not, observing that patients treated with posterior reconstruction had significantly improved time to continence recovery, though long-term recovery was similar between treatment groups [47]. van Randenborgh et al. have previously demonstrated that maximizing membranous urethral length at the time of prostatectomy significantly shortens time to continence recovery and overall continence rates [20]. In a similar vein, Nguyen et al. has proposed that the mechanism for improved early continence recovery with posterior urethral reconstruction is through restoration of membranous urethral length during prostatectomy [48]. However, the role for posterior support reconstruction is still controversial. A systematic review by Rocco et al. found that posterior reconstruction significantly improves early return to function within 30 days of surgery (p = 0.004), though continence rates by 90 days after surgery were not affected [49]. A subsequent systematic review did show a benefit at 90 days, but longer-term benefits have yet to be demonstrated [50]. Combined anterior and posterior reconstruction techniques have also been reported, demonstrating improved early return of continence (<3 months) without an increase in complications [51, 52]. Based on current data, more investigation is required before reconstruction of the periurethral supporting structures becomes standard of care.

The anatomy of the neurovascular bundles has been elucidated in the literature [53–56]. The pudendal nerve innervates the voluntary striated sphincter [57]. Branches of the pudendal nerve are thought to also form a component of the neurovascular bundles and provide innervation to the urethral sphincter complex [53]. Damage to the neurovascular bundle(s) during prostatectomy may disrupt function of the urethral sphincter complex with resultant urinary incontinence. Burkhard et al. prospectively followed 536 patients who had either bilateral, unilateral, or non-nerve-sparing radical prostatectomy and evaluated continence status over a minimum 1-year follow-up period [58]. At 1-year incontinence was found in 1.3%, 3.4%, and 13.7% for bilateral, unilateral, and non-nerve-sparing prostatectomy patients, respectively. On multivariate analysis, the only statistically significant factor influencing urinary incontinence was attempted nerve sparing (p < 0.001). More contemporary data support these findings [59, 60]. However, Marien and Lepor did not observe a difference in continence rates between nerve-sparing and non-nerve-sparing techniques in a prospective cohort of 1110 men [61].

As mentioned above, fibrosis plays a role in the development of postprostatectomy incontinence likely through negative effects on external urethral sphincter function [21, 35]. Studies have also demonstrated that the presence of vesicourethral anastomotic stricture may be a significant risk factor for the development of urinary incontinence after radical prostatectomy [62].

Our understanding of the impact of surgeon experience and prostatectomy modality on urinary outcomes continues to evolve. Evidence exists supporting the notion that more experienced surgeons yield better urinary continence outcomes when compared to less experienced surgeons [39, 63].

The evidence supporting one prostatectomy modality (open, laparoscopic, robotic-assisted) over another with regard to continence outcomes is variable, though in general no significant difference in continence outcomes has been observed when comparing the three modalities, as evidenced by a recent systematic review and meta-analysis [64]. The true impact of prostatectomy modality on continence outcomes will be better characterized as surgeon experience increases with robotic technology and new studies become available.

Urinary incontinence is a known adverse complication in the treatment of localized prostate cancer with radiotherapy [65]. Limited studies have investigated the impact of adjuvant radiotherapy on urinary outcomes following prostatectomy. Petrovich et al. [66] reported no difference in incontinence in two cohorts of patients, one with and one without adjuvant radiation. In a follow-up study the same group reported no late toxicity [67]. Suardi et al. evaluated 361 patients treated with radical prostatectomy and stratified into those receiving adjuvant radiation (n = 153) versus those who did not (n = 208) [68]. At the 1- and 3-year follow-up intervals, continence rates were 51% and 59% versus 81% and 87% for adjuvant radiation therapy versus no radiation, respectively. Fontaine et al. also reported no change in continence status in 16 of 17 men after salvage radiation [69]. However, Petroski et al. reported that postoperative radiotherapy worsened continence in 26% of 129 patients followed for a median of 5 years [70]. Sowerby et al. [71] reported urinary incontinence at 3 years in 24.5% of 162 men who underwent adjuvant radiation and 23.5% of 490 men who underwent delayed or salvage radiation for prostate cancer.

On the other hand, salvage radical prostatectomy following external beam radiotherapy has been generally reported to have a high incidence of urinary incontinence [72–76] possibly because of radiation-induced fibrosis of the external sphincter. [73] In a recent systematic review of 27 series of salvage prostatectomy, Matei et al. [75] reported a 47.8% average incontinence rate (range 19–79%). The incontinence rate was not lower with laparoscopic or robotic approaches. Cozzarini et al. demonstrated that older age and greater radiation dose in the salvage setting and younger age and hypertension in the adjuvant setting resulted in worse “urinary toxicity” [77].