Hypothesis / aims of study
The prevalence of urinary incontinence after radical prostatectomy (PRPUI) is estimated to be as high as 87% depending on definition and study (1), and can severely impact the patient’s quality of life. PRPUI can arise due to intrinsic sphincter deficiency (neurogenic or caused by sphincter damage), due to pre-existing or de novo bladder dysfunction [such as detrusor overactivity (DO), detrusor underactivity (DU) or poor bladder compliance], or due to a combination of both (1).
First-line treatment of PRPUI [lifestyle interventions, medication or physiotherapy (pelvic floor muscle therapy and / or bladder training)] is based on a patient’s history and lower urinary tract symptoms (LUTS), and on non-invasive tests (bladder diary, uroflowmetry and measurement of post-void residual). Prior to second-line invasive treatment, urodynamic studies (UDS) are performed to determine which factors are at play. When stress urinary incontinence (SUI) surgery [male sling or artificial urinary sphincter (AUS)] is considered, it may be important to identify concomitant bladder dysfunction as it would occur after treatment of SUI (treatment simulating UDS). Bladder dysfunction may cause more or other bothersome LUTS after SUI relief, possibly negatively impacting a patient’s satisfaction with the procedure.
The aim of this study was to evaluate the prevalence of urodynamic bladder dysfunction in a large group of patients with PRPUI and to study its correlation with bothersome post-AUS implantation LUTS.
Study design, materials and methods
In this retrospective study, we evaluated the UDS outcomes of 101 patients with first-line therapy refractory PRPUI investigated in our tertiary referral center between May 2013 and September 2018. UDS were performed according to the recommendations by the International Consultation on Incontinence. Leakage of urine was prevented until the patient reported a strong desire to void, until bladder pressure rose above 40cmH2O or until the bladder was filled to 700mL.
Age, time since radical prostatectomy (months) and a history of radiotherapy or SUI surgery were recorded from the patient file or referral letter. Sensations of bladder filling (first sensation of bladder filling, normal desire to void and strong desire to void), maximum cystometric capacity, DO and poor bladder compliance were extracted from the UDS report, and were recorded while leakage was prevented. The presence of DU, bladder outlet obstruction (BOO) and straining during voiding were also extracted from the UDS report. Bladder dysfunction was defined as the presence of at least one of DO, poor bladder compliance, DU or BOO.
The presence of post-operative urinary retention, bothersome urgency urinary incontinence (UUI) or bothersome overactive bladder (OAB) symptoms was extracted from the patient’s follow-up.
In our center, PRPUI, caused by intrinsic sphincter deficiency, is treated with implantation of an AUS. Candidates for male sling are referred to a different hospital. SUI surgery was considered to be contraindicated if patients had a low maximum cystometric capacity and / or poor bladder compliance on pre-operative UDS.
As this was a retrospective anonymised analysis of patient data, approval from the local ethical committee and informed consent from the patients were not required.
Statistical analysis was performed with SPSS 25 (IBM). Categorical variables were compared using Chi square analysis with a Fisher’s exact correction when applicable. Continuous variables were compared using an independent student’s T-test. Significance was set at p<0.05.
Results
Demographic data and UDS parameters are shown in Table 1. Mean follow-up after AUS implantation was 13.1 ± 3.0 months.
Based on the urodynamic findings of low maximum cystometric capacity and / or poor bladder compliance, AUS was considered contraindicated in 17% of patients. In another 9%, AUS was not considered the appropriate treatment option (e.g. due to only nocturnal loss of urine, urgency predominant UI, improvement with first-line treatment after all, or presumed inability to operate the device).
In patients who received an AUS (5 are still on the waiting list), the pre-operative urodynamic presence of bladder dysfunction was not associated with post-AUS urinary retention, UUI or bothersome OAB symptoms (all p=1.000). In specific, DO and a decrease in bladder compliance were not associated with post-AUS UUI or bothersome OAB symptoms in these patients, nor with post-AUS urinary retention (all p>0.05). Similarly, DU and BOO were not associated with post-AUS urinary retention, nor with post-AUS UUI or bothersome OAB symptoms (all p>0.05). Finally, the different sensations of bladder filling and the maximum cystometric capacity were not related to post-AUS UUI or bothersome OAB symptoms (all p>0.05).
Interpretation of results
Preventing leakage during UDS in patients with PRPUI refractory to first-line treatment reveals a high prevalence of bladder dysfunction. Ninety six percent of patients experience at least one bladder dysfunction, with DU being the most prevalent in 70% of patients. The prevalences found in our study are higher than what was previously reported (1), which may be due to the treatment simulating technique, allowing the bladder to fill to maximum cystometric capacity without leaking, and hence allowing adequate pressure-flow studies.
This technique also allowed us to advise 17 patients against an AUS, due to a low maximum cystometric capacity and / or a dangerously poor bladder compliance (which may put the upper urinary tract at risk when the leak point pressure is increased by implantation of an AUS).
Even after contra-indicating an AUS in patients with severe bladder dysfunction, the prevalence of post-AUS urinary retention, UUI and bothersome OAB symptoms remains quite high (11%, 19% and 19% respectively). However, despite the high prevalence of both pre-operative urodynamic bladder dysfunction and of post-operative bothersome LUTS, no statistically significant correlation could be found between them, suggesting that bladder function changes quickly after SUI surgery (recovery and / or new bladder dysfunction), that the correct predictive parameters or stratification has not been identified yet, or that the bladder is an unreliable witness in PRPUI as well.