Impact of surgically maximized versus native membranous urethral length on 30-day and long-term pad-free continence after robot-assisted radical prostatectomy

Association between maximal urethral length preservation and postoperative continence after robot-assisted radical prostatectomy: a meta-analysis and systematic review

ABSTRACT

Urinary incontinence is a common complication following robot-assisted radical prostatectomy (RARP). Urethral length has been identified as a factor affecting postoperative continence recovery. In this meta-analysis, we examined the association between use of the maximal urethral length preservation (MULP) technique and postoperative urinary continence in patients undergoing RARP. We conducted a comprehensive search of PubMed, Web of Science, Embase, and the Cochrane Library up to December 31, 2023. The quality of the literature was assessed using the Newcastle-Ottawa Scale. A random-effects meta-analysis was performed to synthesize data and calculate the odds ratio (OR) from eligible studies on continence and MULP. Six studies involving 1869 patients met the eligibility criteria. MULP was positively associated with both early continence (1 month after RARP; Z = 3.62, P = 0.003, OR = 3.10, 95% confidence interval [CI]: 1.68-5.73) and late continence (12 months after RARP; Z = 2.34, P = 0.019, OR = 2.10, 95% CI: 1.13-3.90). Oncological outcomes indicated that MULP did not increase the overall positive surgical margin rate or the positive surgical margin status at the prostate apex (both P > 0.05). In conclusion, the use of the MULP technique in RARP significantly improved both early and late postoperative continence outcomes without compromising oncological outcomes.

Early recovery of urinary continence after robot-assisted radical prostatectomy is associated with membranous urethra and neurovascular bundle preservation

OBJECTIVES

We investigated the correlation between surgical outcomes and postoperative urinary continence recovery in robot-assisted radical prostatectomy (RARP).

METHODS

Patients who underwent RARP in our institution (n = 195) were included in this study. Preserved urethral length (PUL) was assessed during the procedure. Other outcomes of the surgical procedure were collected from operative records. Kaplan-Meier analysis with log-rank test was used to compare urinary continence recovery rate with the PUL, sparing of the neurovascular bundle (NVB), and other surgical procedures. Univariate and multivariate analyses were performed using Cox proportional hazards model, and p-values of <0.05 were considered significant.

RESULTS

Patients with a PUL ≥26 mm had 10.0%, 24.7%, 36.6%, and 89.0% continence recovery rates at 30, 60, 90, and 365 days after surgery, respectively, while patients with a PUL <26 mm had 0%, 17.8%, 26.1%, and 80.9% recovery rates, respectively. Kaplan-Meier curves showed significantly better postoperative urinary continence recovery at 30 days after RARP in patients with a PUL ≥26 mm than those with a PUL <26 mm (p = 0.0028) and in patients with NVB preservation than those with no NVB preservation (p = 0.014). Urinary continence recovery within 30, 60, and 90 days after surgery was 90.6% for patients with a PUL of ≥26 mm and NVB preservation, while only 82.3% for patients with a PUL of <26 mm or no NVB preservation.

CONCLUSION

Our results suggest that a PUL ≥26 mm and NVB preservation after RARP correlate with a significantly higher postoperative rate of recovery of urinary continence.

Membranous urethral length measurement on preoperative MRI to predict incontinence after radical prostatectomy: a literature review towards a proposal for measurement standardization

OBJECTIVES

To investigate the membranous urethral length (MUL) measurement and its interobserver agreement, and propose literature-based recommendations to standardize MUL measurement for increasing interobserver agreement. MUL measurements based on prostate MRI scans, for urinary incontinence risk assessment before radical prostatectomy (RP), may influence treatment decision-making in men with localised prostate cancer. Before implementation in clinical practise, MRI-based MUL measurements need standardization to improve observer agreement.

METHODS

Online libraries were searched up to August 5, 2022, on MUL measurements. Two reviewers performed article selection and critical appraisal. Papers reporting on preoperative MUL measurements and urinary continence correlation were selected. Extracted information included measuring procedures, MRI sequences, population mean/median values, and observer agreement.

RESULTS

Fifty papers were included. Studies that specified the MRI sequence used T2-weighted images and used either coronal images (n = 13), sagittal images (n = 18), or both (n = 12) for MUL measurements. 'Prostatic apex' was the most common description of the proximal membranous urethra landmark and 'level/entry of the urethra into the penile bulb' was the most common description of the distal landmark. Population mean (median) MUL value range was 10.4-17.1 mm (7.3-17.3 mm), suggesting either population or measurement differences. Detailed measurement technique descriptions for reproducibility were lacking. Recommendations on MRI-based MUL measurement were formulated by using anatomical landmarks and detailed descriptions and illustrations.

CONCLUSIONS

In order to improve on measurement variability, a literature-based measuring method of the MUL was proposed, supported by several illustrative case studies, in an attempt to standardize MRI-based MUL measurements for appropriate urinary incontinence risk preoperatively.

CLINICAL RELEVANCE STATEMENT

Implementation of MUL measurements into clinical practise for personalized post-prostatectomy continence prediction is hampered by lack of standardization and suboptimal interobserver agreement. Our proposed standardized MUL measurement aims to facilitate standardization and to improve the interobserver agreement.

KEY POINTS

• Variable approaches for membranous urethral length measurement are being used, without detailed description and with substantial differences in length of the membranous urethra, hampering standardization. • Limited interobserver agreement for membranous urethral length measurement was observed in several studies, while preoperative incontinence risk assessment necessitates high interobserver agreement. • Literature-based recommendations are proposed to standardize MRI-based membranous urethral length measurement for increasing interobserver agreement and improving preoperative incontinence risk assessment, using anatomical landmarks on sagittal T2-weighted images.

Association between 3D membranous urethral parameters and urinary continence recovery after RARP

OBJECTIVES

To evaluate whether the urinary continence (UC) recovery after robotic-assisted radical prostatectomy (RARP) relates to the membranous urethral length (MUL) and the membranous urethral complex volume (MUV).

MATERIALS AND METHODS

120 patients who underwent RARP were enrolled according to the different times of UC recovery and examined using prostate magnetic resonance imaging (MRI) before surgery. The membranous urethral (MU) parameters were measured using the three-Dimensional (3D) model reconstructed by holographic technology, such as total MUV (tMUV), exposed MUV (eMUV), full MUL (fMUL) and exposed MUL (eMUL). Statistical software SPSS 26.0 was used to analyze the data and compare the MU parameters and baseline data in different groups.

RESULTS

Patients with larger tMUV (p = 0.038), eMUV (p = 0.003), longer fMUL (p = 0.025), eMUL (p = 0.044) had better UC after removal of the catheter, and eMUV (OR = 1.002, 95%CI = 1.001-1.004, p = 0.004) was a predictor; the patients with younger age (p = 0.021), lower VPSS score (p = 0.004) and larger eMUV (p = 0.012) and longer eMUL (p = 0.049) had better UC recovery one month after RARP while eMUV (OR = 1.002, 95% CI = 1.000-1.003, p = 0.008) and VPSS score (OR = 0.886, 95% CI = 0.806-0.973, p = 0.011) were independent risk factors; The patients with younger age (p = 0.018), larger tMUV (p = 0.029), eMUV (p = 0.016) had better UC recovery three months after RARP. eMUV (OR = 1.002, 95% CI = 1.000-1.004, p = 0.042) and age (OR = 0.904, 95% CI = 0.818-0.998, p = 0.046) were independent risk factors.

CONCLUSION

This clinical study shows that patients with larger MUV and longer MUL can return to UC earlier after surgery. Among that, eMUV is a better predictor.

An artificial intelligence method for predicting postoperative urinary incontinence based on multiple anatomic parameters of MRI

Background

Deep learning methods are increasingly applied in the medical field; however, their lack of interpretability remains a challenge. Captum is a tool that can be used to interpret neural network models by computing feature importance weights. Although Captum is an interpretable model, it is rarely used to study medical problems, and there is a scarcity of data regarding MRI anatomical measurements for patients with prostate cancer after undergoing Robotic-Assisted Radical Prostatectomy (RARP). Consequently, predictive models for continence that use multiple types of anatomical MRI measurements are limited.

Methods

We explored the energy efficiency of deep learning models for predicting continence by analyzing MRI measurements. We analyzed and compared various statistical models and provided reference examples for the clinical application of interpretable deep-learning models. Patients who underwent RARP at our institution between July 2019 and December 2020 were included in this study. A series of clinical MRI anatomical measurements from these patients was used to discover continence features, and their impact on continence was primarily evaluated using a series of statistical methods and computational models.

Results

Age and six other anatomical measurements were identified as the top seven features of continence by the proposed model UINet7 with an accuracy of 0.97, and the first four of these features were also found by primary statistical analysis.

Conclusions

This study fills the gaps in the in-depth investigation of continence features after RARP due to the limitations of clinical data and applicable models. We provide a pioneering example of the application of deep-learning models to clinical problems. The interpretability analysis of deep learning models has the potential for clinical applications.

Predictors of Urinary Continence Recovery after Laparoscopic-Assisted Radical Prostatectomy: Is Surgical Urethral Length the Only Key Factor?

Several efforts in recent years have been made to predict urinary continence (UC) recovery after radical prostatectomy. The aim of our study was to investigate the impact of surgical urethral length preservation (SULP) on urinary continence after LARP (laparoscopic-assisted radical prostatectomy). We retrospectively queried our datasets from May 2021 to May 2022. After the application of exclusion criteria, a total of 100 patients who underwent LARP for prostate cancer at our institution were enrolled. Through a sterile ruler inserted by a 12 mm trocar, the length of the membranous urethra spared during LARP was assessed intra-operatively. The baseline and peri- and postoperative data of patients were collected, and UC was defined as 0 or 1 on a safety pad. The median SULP was 20.5 mm (IQR, 14.5-25), and the median intraoperative EBL were 150 mL (IQR, 100-200). The Kaplan-Meier curve showed a significant difference at 20 mm, which was used as the cut-off value for SULP (log-rank test, p < 0.001). Multivariate Cox proportional hazards models showed that SULP and EBL < 250 mL were associated with UC recovery (all p < 0.02). Surgical urethral length preservation seemed to improve early UC recovery after LARP. Further multicentric studies are needed to confirm our findings.

Evaluating post radical prostatectomy mechanisms of early continence

BACKGROUND

To identify the periprostatic structures associated with early return of urinary continence after radical prostatectomy (RP).

METHODS

We compared total continence results between four different techniques of robot-assisted radical prostatectomy (RARP). Specifically, we studied 1-week and 1-month zero-pad continence rates of anterior (n = 60), posterior (n = 59), a novel hybrid posterior-anterior (n = 12), and transvesical (n = 12) approaches of RARP. Each technique preserved a unique set of periprostatic anatomic structures, thereby, allowing evaluation of the individual impact of preservation of nerves, bladder neck, and space of Retzius with associated anterior support structures on early continence. Urethral length was preserved in all approaches. The space of Retzius was preserved in posterior and transvesical approaches, while the bladder neck was preserved in posterior and hybrid approaches. Nerve sparing was done per preoperative oncological risk. For all patients, 24-h pad usage rates and 24-h pad weights were noted at 1 week and 1 month after catheter removal. Multivariable logistic regression analysis was performed to identify predictors of early continence. Data were obtained from prospective studies conducted between 2015 and 2021.

RESULTS

At 1 week, 15%, 42%, 45%, and 8% of patients undergoing anterior, posterior, hybrid, and transvesical RARP approaches, respectively, were totally continent (p = 0.003). These rates at 1 month were 35%, 66%, 64%, and 25% (p = 0.002), respectively. The transvesical approach, which preserved the space of Retzius but not the bladder neck, was associated with the poorest continence rates, while the posterior and hybrid approaches in which the bladder neck was preserved with or without space of Retzius preservation were associated with quickest urinary continence recovery. Bladder neck preservation was the only significant predictor of 1-week and 1-month total continence recovery in adjusted analysis, Odds ratios 9.06 (p = 0.001) and 5.18 (p = 0.004), respectively.

CONCLUSIONS

The beneficial effect of the Retzius-sparing approach on early continence recovery maybe associated with bladder neck preservation rather than space of Retzius preservation.

Value of Different Magnetic Resonance Imaging-based Measurements of Anatomical Structures on Preoperative Prostate Imaging in Predicting Urinary Continence After Radical Prostatectomy in Men with Prostate Cancer: A Systematic Review and Meta-analysis

CONTEXT

Measurements of anatomical structures on preoperative prostate magnetic resonance imaging (MRI) are used in risk models for treatment decisions to predict urinary continence (UC) following radical prostatectomy (RP). However, the association between these parameters and UC is unclear.

OBJECTIVE

To systematically summarize the literature on prognostic preoperative prostate MRI measurements of (peri)prostatic structures in relation to time to recovery of postoperative UC in men with prostate cancer.

EVIDENCE ACQUISITION

Online libraries were searched up to August 27, 2021. Article selection and critical appraisal were performed by two reviewers. All papers reporting on preoperative MRI measurements with UC correlation in univariable or multivariable analyses were included.

EVIDENCE SYNTHESIS

In the 50 studies included (mostly retrospective), 57 MRI parameters were evaluated. The pooled analyses showed that greater membranous urethra length (MUL) was prognostic for regaining UC at 1 mo (odds ratio [OR] 1.15, 95% confidence interval [CI] 1.10-1.21), 3 mo (OR 1.23, 95% CI 1.16-1.31), 6 mo (OR 1.16, 95% CI 1.08-1.25), and 12 mo (OR 1.19, 95% CI 1.10-1.29). Several other anatomical structures showed at least in one study a significant correlation with later return to UC: four prostate-related parameters (greater depth, apical protrusion, larger intravesical protrusion, small dorsal vascular complex), five urethra-related parameters (thicker wall, severe fibrosis, smaller volume, larger preoperative angle between the prostate axis and membranous urethra, shorter minimal residual MUL), and six musculoskeletal-related parameters (lower perfusion ratio, thinner levator ani muscle, larger inner or outer levator distance, shorter pelvic diaphragm length, and larger midpelvic area).

CONCLUSIONS

Greater MUL as measured on preoperative MRI was an independent prognostic factor for return to UC within 1 mo after RP and remained prognostic at 12 mo. Other anatomical structures may potentially be predictive, but these would need to be substantiated in prospective trials before being adopted in postoperative UC risk models for treatment decisions in men with prostate cancer.

PATIENT SUMMARY

We summarized study data on the relation between measurements of anatomical structures on preoperative magnetic resonance imaging scans and urinary continence after removal of the prostate. Greater length of one part of the urethra (membranous urethra) is associated with faster return to continence. Other anatomical structures have potential for predicting postoperative continence, but need further investigation.

Retzius-sparing versus modified anatomical structures preserving and retzius repairing robotic-assisted radical prostatectomy: A prospective randomized comparison on functional outcomes with a 1-year follow-up

Objectives; To compare the short-term and 1-yr follow-up functional outcomes of modified anatomical structures preserving and retzius-repairing robot-assisted radical prostatectomy (APR-RARP) compared with retzius-sparing (RS) RARP. Methods; 80 consecutive patients aged 40-75 yr with low-intermediate risk prostat cancer (PCa) were prospectively randomized to APR-RARP or RS-RARP. Urinary continence (UC) recovery rates were evaluated from catheter removal up to 1 yr follow-up. Postoperative UC was defined as 0 pads/one security pad per day. UC recovery rates from catheter removal to 1 yr were calculated by Kaplan-Meier curve; log-rank test was used for the curve comparison. Postoperative potency was evaluated at 3 and 12 months after surgeries. Perioperative complications, positive surgical margin (PSM), and biochemical recurrence rates represent secondary outcomes reported in the study. Results; At the catheter removal, 1, 3, 6 and 12 months after surgery, 52.5% (CI% 95% 37.6-67), 82.5% (CI% 95% 70.8-94), 95% (CI% 95% 88.3-99.1), 97.5% (CI% 95% 92.5-99.9) and 97.5% (CI% 95% 92.5-99.9) of men undergoing the APR-RARP were continent (0 pads/one security pad per day), compared with 61.5% (CI% 95% 46.5-76.6), 89.7% (CI% 95% 80.3-98.1), 97.5% (CI% 95% 92.6-99.9), 97.5% (CI% 95% 92.6-99.9) and 97.5% (CI% 95% 92.6-99.9) undergoing the RS-RARP, respectively, and the Kaplan Meier curve showed no statistically significant difference for both technique at any time point (log-rank p = 0.556). The median (95% confidence interval [CI]) time to UC recovery was 9.8 (5.2-14.4) days for the APR-RARP versus 6.7 (3.2-10.2) days for the RS-RARP group. Potency rates were similar in both groups at 3 and 12 months after surgeries. The two compared approaches, in terms of rate of complications, PSM were similar. Conclusions; Surgeons can achieve functional results comparable to the retzius-sparing technique with the modified reconstructive anterior approach, without changing the surgical technique they are used to.

Longer preserved urethral length in robot‐assisted radical prostatectomy significantly contributes to post‐operative urinary continence recovery

Objectives

To assess the relationship between the surgical procedure of robot‐assisted radical prostatectomy (RARP) and urinary continence recovery by reviewing the video database.

Methods

Video and data about men diagnosed with prostate cancer and underwent RARP were extracted and reviewed. Preserved urethral length (PUL) was semi‐quantitatively measured using the lateral width of a 16‐Fr urethral balloon catheter while cutting the urethra on a video screen. In addition, by reviewing intraoperative RARP video database, other surgical skill outcomes were also collected. Kaplan–Meier analysis with log‐rank test was used to compare the urinary continence recovery rate, stratified by the PUL. Univariate and multivariate analyses were performed using the Cox proportional hazards model, and p‐values of <0.05 were considered significant.

Results

The number of patients included in this study was 213. In univariate analysis, a PUL of ≥16 mm, a body mass index of <23.1 kg/m² and a resected prostate volume of <44.3 g were statistically significant factors that influenced urinary continence recovery [hazard ratio (HR) 1.58, p = 0.036; HR 0.67, p = 0.021; and HR 0.58, p = 0.005, respectively]. Those factors also remained statistically significant in the multivariate analysis (HR 1.87, p = 0.022; HR 0.54, p = 0.001; and HR 0.57, p = 0.005, respectively). One year post‐operatively, the recovery rate from urinary continence was 79.0% for patients with a PUL of ≥16 mm and 66.5% for patients with a PUL of <16 mm.

Conclusion

These results suggest that patients with longer PUL in RARP have a significantly higher rate of post‐operative urinary continence recovery.

Patient- and Tumour-related Prognostic Factors for Urinary Incontinence After Radical Prostatectomy for Nonmetastatic Prostate Cancer: A Systematic Review and Meta-analysis

CONTEXT

While urinary incontinence (UI) commonly occurs after radical prostatectomy (RP), it is unclear what factors increase the risk of UI development.

OBJECTIVE

To perform a systematic review of patient- and tumour-related prognostic factors for post-RP UI. The primary outcome was UI within 3 mo after RP. Secondary outcomes included UI at 3-12 mo and ≥12 mo after RP.

EVIDENCE ACQUISITION

Databases including Medline, EMBASE, and CENTRAL were searched between January 1990 and May 2020. All studies reporting patient- and tumour-related prognostic factors in univariable or multivariable analyses were included. Surgical factors were excluded. Risk of bias (RoB) and confounding assessments were performed using the Quality In Prognosis Studies (QUIPS) tool. Random-effects meta-analyses were performed for all prognostic factor, where possible.

EVIDENCE SYNTHESIS

A total of 119 studies (5 randomised controlled trials, 24 prospective, 88 retrospective, and 2 case-control studies) with 131 379 patients were included. RoB was high for study participation and confounding; moderate to high for statistical analysis, study attrition, and prognostic factor measurement; and low for outcome measurements. Significant prognostic factors for postoperative UI within 3 mo after RP were age (odds ratio [OR] per yearly increase 1.04, 95% confidence interval [CI] 1.03-1.05), membranous urethral length (MUL; OR per 1-mm increase 0.81, 95% CI 0.74-0.88), prostate volume (PV; OR per 1-ml increase 1.005, 95% CI 1.000-1.011), and Charlson comorbidity index (CCI; OR 1.28, 95% CI 1.09-1.50).

CONCLUSIONS

Increasing age, shorter MUL, greater PV, and higher CCI are independent prognostic factors for UI within 3 mo after RP, with all except CCI remaining prognostic at 3-12 mo.

PATIENT SUMMARY

We reviewed the literature to identify patient and disease factors associated with urinary incontinence after surgery for prostate cancer. We found increasing age, larger prostate volume, shorter length of a section of the urethra (membranous urethra), and lower fitness were associated with worse urinary incontinence for the first 3 mo after surgery, with all except lower fitness remaining predictive at 3-12 mo.

Effect of prostatic apex shape (Lee types) and urethral sphincter length in preoperative MRI on very early continence rates after radical prostatectomy

Purpose

To test the effect of anatomic variants of the prostatic apex overlapping the membranous urethra (Lee type classification), as well as median urethral sphincter length (USL) in preoperative multiparametric magnetic resonance imaging (mpMRI) on the very early continence in open (ORP) and robotic-assisted radical prostatectomy (RARP) patients.

Methods

In 128 consecutive patients (01/2018–12/2019), USL and the prostatic apex classified according to Lee types A–D in mpMRI prior to ORP or RARP were retrospectively analyzed. Uni- and multivariable logistic regression models were used to identify anatomic characteristics for very early continence rates, defined as urine loss of ≤ 1 g in the PAD-test.

Results

Of 128 patients with mpMRI prior to surgery, 76 (59.4%) underwent RARP vs. 52 (40.6%) ORP. In total, median USL was 15, 15 and 10 mm in the sagittal, coronal and axial dimensions. After stratification according to very early continence in the PAD-test (≤ 1 g vs. > 1 g), continent patients had significantly more frequently Lee type D (71.4 vs. 54.4%) and C (14.3 vs. 7.6%, p = 0.03). In multivariable logistic regression models, the sagittal median USL (odds ratio [OR] 1.03) and Lee type C (OR: 7.0) and D (OR: 4.9) were independent predictors for achieving very early continence in the PAD-test.

Conclusion

Patients’ individual anatomical characteristics in mpMRI prior to radical prostatectomy can be used to predict very early continence. Lee type C and D suggest being the most favorable anatomical characteristics. Moreover, longer sagittal median USL in mpMRI seems to improve very early continence rates.

Cine magnetic resonance imaging provides novel predictors of early continence recovery after radical prostatectomy: Assessment of the dynamics of pelvic floor muscles

AIMS

Postprostatectomy incontinence is a major complication of prostatectomy. Although pelvic floor muscle training can successfully treat postprostatectomy incontinence, evidence for how muscle movement affects continence recovery is lacking. We evaluated dynamic factors of prostatectomy patients using cine magnetic resonance imaging to identify risk factors for postprostatectomy incontinence and reveal the contribution of pelvic floor muscles to continence recovery.

METHODS

A total of 128 prostate cancer patients who underwent robot-assisted laparoscopic surgery were enrolled. Cine magnetic resonance imaging was performed preoperatively and 6 months after surgery. Continence was defined as pad-free or use of safety pads. We defined the bladder neck elevation distance during pelvic floor muscle training as the bladder elevation distance. Patients with continence recovery within 1 month comprised the continence group (n = 48); other patients comprised the incontinence group (n = 80).

RESULTS

The preoperative bladder elevation distance was significantly longer in the continence group than in the incontinence group (10.4 vs. 8.2 mm; p < .001). The postoperative bladder elevation distance of the continence group tended to be longer (9.9 vs. 8.9 mm; p = .057). Multivariate analysis showed that the preoperative bladder elevation distance significantly contributed to continence recovery (p = .016). Patients with a longer preoperative bladder elevation distance (>8.5 mm) experienced continence recovery significantly faster than patients with a shorter distance (<8.5mm) (p = .038).

CONCLUSIONS

Bladder elevation distance, a novel dynamic parameter, was strongly associated with early continence recovery. Cine magnetic resonance imaging can assess a patient's risk of postprostatectomy incontinence and guide pelvic floor muscle training.