According to Dr. Comiter it is important to ask a question whose answer affects the treatment algorithm. Is incontinence due to intrinsic sphincter deficiency? Detrusor overactivity? Both? Is it related to compliance? Is there bladder outlet obstruction? Can the bladder contract adequately? In his opinion, if there is no question, then urodynamics is not indicated. Dr. Comiter notes that the characterization of stress urinary incontinence can affect decision making, in that urethral mobility, affects transobturator sling outcomes, and the degree of urethral mobility may vary in different patients. High urethral mobility is often seen after radical prostatectomy without radiation, whereas the lowest urethral mobility is seen in patients that have received radiation therapy. Dr. Comiter advocates the urethral repositioning test whereby elevation of the perineum by the examiner during urethroscopy, and by sling tensioning, allows contraction of the external urinary sphincter.
A positive test is as follows:
Whereas a negative test is as follows:
Sustained sling tension is necessary for continence and over-correction can lead to urinary retention and under-correction can lead to recurrent incontinence. Furthermore, adequate contractility is needed to overcome the resistance of a compressive sling, and a potentially obstructive sling in the setting of detrusor underactivity poses the risk of urinary retention. By nature, a sling is designed to prevent leakage with straining and therefore interferes/prevents voiding by Valsalva.
Dr. Comiter states that it is important to correctly check detrusor underactivity and that the use of surrogate measures based on BPH literature to identify detrusor underactivity can be inaccurate in men who have had their prostate removed. He advocates for the use of isovolumetric detrusor pressure (Piso), noting that a Piso <50 cm of water is suggestive of detrusor underactivity. In a study from his group, they assessed 62 men referred to our institution during a 3-year period for workup of post-prostatectomy incontinence finding that the mean Piso was 54.6 ± 25.4 cm H2O, and Piso was <50 cm H2O in 40% of men. Isometric strength did not significantly correlate with age, interval since radical prostatectomy, abdominal leak point pressure, maximal urethral closure pressure, or pad use.
Measuring contractility affects treatment choice in that patients with a weak bladder should be considered for a transobturator sling for mild incontinence, whereas quadratic (adjustable) slings are contraindicated in these patients. For patients with normal contractility, all options are on the table: (i) a transobturator sling for mild incontinence, (ii) an adjustable sling for moderate and, and even severe incontinence among those that don’t want an artificial urinary sphincter, and (iii) an artificial urinary sphincter is always an option as primary or salvage treatment for these patients.
Dr. Comiter does feel that urodynamics is indicated following failed sling surgery for stress urinary incontinence. He notes that the patient has already been disappointed twice (incontinent after prostate cancer treatment and incontinence after continence surgery), thus it is imperative to know everything necessary in order to provide the best recommendation. When to re-intervene for continued incontinence is likely multifactorial:
- When the patient is dissatisfied with bothersome stress urinary incontinence and requiring >1 pad per day
- There is a correctable, suboptimal outcome such as the sling slipping, insufficient coaptation, or there is a treatable problem with a new sling or an adjustable old sling (ie. persistent positive repositioning test)
- An artificial sphincter is always an option
- Detrusor overactivity – clinicians should consider bladder-directed therapy
Dr. Comiter stress that if you are not offering urodynamics in the evaluation of post-prostatectomy incontinence, you must find a way to answer all of the relevant questions:
- Intrinsic sphincter deficiency versus detrusor overactivity: history and physician examination
- Sphincteric function: repositioning test during cystoscopy
- Degree of incontinence: pad weight/pad test
- Bladder contractility: This cannot be done without urodynamics, however, if the patient has a low post-void residual and a good uroflow without straining, this likely suggests adequate bladder contractility
Dr. Comiter concluded highlighting that urodynamics should be considered for post-prostatectomy incontinence if it answers a question that will change management, but it is not necessary if an artificial urinary sphincter is pre-determined. Urodynamics does determine the suitability of a sling versus an artificial urinary sphincter, which is likely to be determined based on bladder contractility. Furthermore, urodynamics may even help determine which sling is best.
Dr. Mourtzinos started his presentation by noting that the recommendations for urodynamics in the setting of post-prostatectomy incontinence have Grade C recommendations, which means that (i) the balance between benefits and risk/burden is unclear, (ii) alternative strategies may be equally reasonable, and (iii) better evidence is likely to change confidence. Kadono and colleagues2 examined chronological changes in urethral and bladder functions before, immediately after, and 1 year after robotic prostatectomy using prospective urodynamic evaluation. Among 63 patients, they found that mean bladder compliance was 28.3 mL/cm H₂O before robotic prostatectomy, which worsened to 16.3 mL/cm H₂O immediately after surgery and recovered to 27.1 mL/cm H₂O at 1-year post-radical prostatectomy. The mean detrusor pressure at maximum flow rate was 61.9 cm H₂O before robotic prostatectomy, which decreased to 34.3 cm H₂O immediately after surgery and remained at 35.6 cm H₂O at 1-year post-op. Finally, they found that the mean maximum urethral closure pressure was 84.2 cm H₂O before surgery, which decreased to 33.4 cm H₂O immediately after robotic prostatectomy and recovered to 63.0 cm H₂O at 1 year. Dr. Mourtzinos summarized these findings noting that urethral sphincter and bladder function worsen immediately after robotic prostatectomy and recover over time, whereas bladder compliance returns to almost the same level as pre-surgery.
With regards to detrusor overactivity and male slings, Ballert and Nitti assessed 72 patients (52 had detrusor overactivity and 20 did not) and there was no difference in success/failure based on patient questionnaires, as well as no difference in number of pads used post-operatively.3 Based on these results, men with urodynamic stress urinary incontinence and detrusor overactivity may be considered for a male sling procedure provided that the stress urinary incontinence is of sufficient bother. Additional studies have shown that the only predictor of success with a sling is the severity of incontinence and that radiotherapy is typically associated and predictive of poor outcomes.
Dr. Mourtzinos typically offers patients the following based on their symptoms:
- Mild leakage: stress incontinence – pelvic floor physiotherapy or transobturator sling; urge incontinence – follow the overactive bladder guidelines
- Moderate leakage: transobturator sling or quadratic sling or artificial urinary sphincter
- Severe leakage: quadratic sling or artificial urinary sphincter
- History of radiation: artificial urinary sphincter
- Revision surgery: artificial urinary sphincter is still the best option
Dr. Mourtzinos highlighted that clinicians should use urodynamics for evaluating patients with post-prostatectomy incontinence when there is a (i) failed initial procedure, (ii) a history of radiation therapy with mixed incontinence, and (iii) incontinence in the setting of a neurologic disorder such as Parkinson’s disease or multiple sclerosis.
Presented by: Craig Comiter, MD, Stanford University, Palo Alto, CA; Arthur Mourtzinos, MD, MBA, Lahey Institute of Urology, Burlington, MA
Written by: Zachary Klaassen, MD, MSc – Assistant Professor of Urology, Georgia Cancer Center, Augusta University/Medical College of Georgia Twitter: @zklaassen_md at the 2020 American Urological Association (AUA) Annual Meeting, Virtual Experience #AUA20, June 27- 28, 2020
References:
- Elliott CS, Comiter CV. Maximum Isometric Detrusor Pressure to Measure Bladder Strength in Men with Postprostatectomy Incontinence. Urology 2012 Nov;80(5):1111-1115.
- Kadono Y, Ueno S, Iwamoto D, et al. Chronological Urodynamic Evaluation of Changing Bladder and Urethral Functions After Robot-assisted Radical Prostatectomy. Urology 2015 Jun;85(6):1441-1447.
- Ballert KN, Nitti VW. Association between detrusor overactivity and postoperative outcomes in patients undergoing male bone anchored perineal sling. J Urol 2010;183:641.