Hypothesis / aims of study
Stress incontinence (SI) in men is most commonly a result of Radical Retropubic Prostatectomy (RRP). Whilst estimates vary, around 10% of men at one year have mild SI post RRP. It can also occasionally occur following surgery for bladder outlet obstruction, or other pelvic surgery such as low anterior resection of rectum. A number of procedures have been developed to manage SI in men. Nearly all of these procedures carry with them a risk of significant morbidity, including device related infection. Urethral bulking injections are an established treatment of mild stress incontinence in women, and morbidity rates are very low. We present our experience of 24 men with stress incontinence who received urethral bulking injections.
Study design, materials and methods
A 4 year retrospective audit of operating theatre records at our hospital was performed, from August 2014 until August 2018. An electronic search was performed for every male patient who was coded as receiving a cystoscopy and introduction of therapeutic substance. Other cases such as botulinum toxin injections for over activity were excluded. The electronic operation notes were used to create the database of main surgeon, type of injection and indication for surgery. They were also used to identify patients that later received additional surgical treatment for their stress incontinence. Electronic clinic notes were used to assess outcomes of the surgery, surgical complications, aetiology of the incontinence and pre-procedure pad usage.
24 men were identified as having received urethral bulking injections, under the supervision of a single consultant. 32 injections were performed in those men over a four-year period. The same technique was used to administer the agent. All procedures were performed under general or spinal anaesthetic. Via a rigid cystoscope the agent was injected into the perisphincteric region through multiple punctures with a flexible endoscopic needle.
A total of 32 urethral bulking injections were performed in 24 men over 4 years. 92% (22/24) of men had stress incontinence following radical prostatectomy. One patient had urodynamic proven stress incontinence post bladder neck incision and one man had stress incontinence following a low anterior resection. Mean pad usage prior to urethral bulking injections was 2.6 per day (range 1-6).
17 men had one urethral bulking injection procedure, 4 men underwent a second procedure, and 2 men received a total of 3 procedures. 3 men were given botulinum toxin injection to their detrusor in addition to urethral bulking during the same anaesthetic for co-existing detrusor over activity.
8/24 men had previously received a trans-obturator tape (TOT) for SI, but had ongoing problematic urinary leakage. 11/24 men later went on to receive an artificial urinary sphincter/ adjustable urethral sling or requested a long term indwelling catheter to manage their continence after urethral bulking injections.
Only 1/8 (13%) of those who had previously had a surgery for their incontinence was satisfied with the result of injection therapy, and the majority (62%) went on to have either an artificial urinary sphincter or an adjustable urethral sling.
Overall 25% of men were happy with the outcome of injection therapy. However, 55% reported an improvement in those men using 2 pads or fewer per day. No men using >2 pads per day appeared to benefit from injection therapy.
Interpretation of results
Urethral bulking injection is a low risk procedure that can benefit certain subgroups of men with mild stress incontinence. The effectiveness of urethral bulking injections in men appears to be inversely proportional to the degree of incontinence. It works best in men with very mild but troublesome incontinence. About half of men in our series wearing one pad a day were pad free after urethral bulking injections.
The low success rate in the previous TOT population is initially surprising as they overall had a lower mean number of pads used per day, at 1.9/day (range 1-3), than the population overall. It is possible that these men had a greater degree of sphincter dysfunction to begin with, or it may be due to the effect of the tape altering their urethral sphincter anatomy or adding scar tissue. Anecdotally, it seems to be more difficult to “bulk” the perisphincteric region in this group of patients in a similar finding to those that have had pelvic radiotherapy.
Urethral bulking injections do not appear to be effective in men using more than 2 pads a day or those that have received adjuvant pelvic radiotherapy. Complication rates are very low, but satisfaction rates are modest. Half of men in this series went on to have more invasive treatments to manage their stress incontinence.
Injectable urethral bulking agents appear to show some promise with mild stress incontinence in men, but more research is needed. We are currently designing a prospective study to examine the factors that affect the success of injectable agents in men with mild stress incontinence. This will include injection volume, injection placement, and patient factors including those post adjuvant radiotherapy and in men with concurrent urethral strictures.