|Year : 2020 | Volume
| Issue : 1 | Page : 60-63
Management of urethral atrophy after implantation of artificial urinary sphincter: what are the weaknesses?
Nathaniel H Heah1, Ronny B W Tan2
1 Department of Urology, Tan Tock Seng Hospital, 308433 Singapore
2 Advanced Urology, Mount Elizabeth Hospital, 228510 Singapore
|Date of Submission||06-Mar-2019|
|Date of Acceptance||18-Aug-2019|
|Date of Web Publication||15-Nov-2019|
Ronny B W Tan
Advanced Urology, Mount Elizabeth Hospital, 228510
Source of Support: None, Conflict of Interest: None
The use of artificial urinary sphincter (AUS) for the treatment of stress urinary incontinence has become more prevalent, especially in the “prostate-specific antigen (PSA)-era”, when more patients are treated for localized prostate cancer. The first widely accepted device was the AMS 800, but since then, other devices have also entered the market. While efficacy has increased with improvements in technology and technique, and patient satisfaction is high, AUS implantation still has inherent risks and complications of any implant surgery, in addition to the unique challenges of urethral complications that may be associated with the cuff. Furthermore, the unique nature of the AUS, with a control pump, reservoir, balloon cuff, and connecting tubing, means that mechanical complications can also arise from these individual parts. This article aims to present and summarize the current literature on the management of complications of AUS, especially urethral atrophy. We conducted a literature search on PubMed from January 1990 to December 2018 on AUS complications and their management. We review the various potential complications and their management. AUS complications are either mechanical or nonmechanical complications. Mechanical complications usually involve malfunction of the AUS. Nonmechanical complications include infection, urethral atrophy, cuff erosion, and stricture. Challenges exist especially in the management of urethral atrophy, with both tandem implants, transcorporal cuffs, and cuff downsizing all postulated as potential remedies. Although complications from AUS implants are not common, knowledge of the management of these issues are crucial to ensure care for patients with these implants. Further studies are needed to further evaluate these techniques.
Keywords: artificial urinary sphincter; artificial urinary sphincter complications; tandem cuffs; transcorporal cuffs; urethral atrophy
|How to cite this article:|
Heah NH, Tan RB. Management of urethral atrophy after implantation of artificial urinary sphincter: what are the weaknesses?. Asian J Androl 2020;22:60-3
|How to cite this URL:|
Heah NH, Tan RB. Management of urethral atrophy after implantation of artificial urinary sphincter: what are the weaknesses?. Asian J Androl [serial online] 2020 [cited 2020 Feb 24];22:60-3. Available from: http://www.ajandrology.com/text.asp?2020/22/1/60/271073 - DOI: 10.4103/aja.aja_110_19
| Introduction|| |
Significant stress urinary incontinence (SUI) is a source of psychological stress for many men. For patients with significant SUI, the placement of an artificial urinary sphincter (AUS) can greatly improve leakage rates, and overall quality of life, and remains the treatment of choice for moderate-to-severe SUI.
Particularly, while most commonly performed after radical prostatectomy, the use of AUS for significant SUI has also been reported after transurethral resection of prostate (TURP), cystoprostatectomy with neobladders, and in patients with neurogenic bladders. Importantly, the success of AUS implantation is consistent across most etiologies of SUI.,
The AUS itself is a robust device; however, the risk of reoperation can still be as high as 25%–34%.,, Although the complication and reoperation rates have improved from historical data, clinicians still need an armamentarium of techniques to salvage AUS complications. In general, reasons for revision can be usually divided into mechanical and nonmechanical failures. Mechanical failures are due to defects or failure of the AUS itself and can be remedied with replacement of the device with good results. However, challenges remain with nonmechanical failures. The most common reasons for nonmechanical revisions are urethral atrophy and urethral erosion. The aim of this review is to analyze the data regarding urethral atrophy, and the various techniques that have been used to address this aspect of nonmechanical failure, while continuing strive for good continence rates for patients.
| AUS Complications|| |
The most common AUS device currently on the market is the AMS 800 (Boston Scientific, MA, USA) device, although there are alternative devices available, such as the Flow-Secure© (Sphinx Medical, Bellshill, North Lanarkshire, United Kingdom), Periurethral Constrictor (Silimed, Rio de Janeiro, Brazil), and ZSI 375 (ZEPHYR Surgical Implants, Geneva, Switzerland) as shown in [Figure 1]. The currently available AUS implants are complex devices and combine several components to achieve the desired continence result, and the overall mechanical failure rate is 6.2% (2.0%–13.8%). These complications have been reported to occur from as early as 11–68.1 months postinsertion. The AMS 800, which is the most studied device, consists of a urethral cuff, pressure-regulating balloon (PRB), and control pump, which are all connected with tubing. While all components are susceptible to failure, the urethral cuff is the most common component to fail. While their durability is robust, certain patterns in the failure of the device itself have been observed. For the AMS 800, the use of the 3.5-cm cuff has been shown to be associated with a higher mechanical failure rate when compared to the 4-cm cuff (hazard ratio [HR]: 7.313, P < 0.0001). Loh-Doyle et al. found in a retrospective study consisting of 993 individual cases that the urethral cuff was the most common component to fail. Subgroup analysis of this population found that the 3.5-cm cuff was at higher risk of failure on Cox regression modeling, and the incidence of cuff failure was distributed evenly over the 5-year follow-up of patients, leading the authors to postulate that this could inherent to the cuff itself. Analysis of the explanted cuffs revealed that leaks tended to form in the creases of the 3.5-cm cuff when inflated, which is a unique trait of the smaller cuff. The introduction of the narrow backing cuff also coincided with a drop in the mechanical failure rate of the AUS.,
|Figure 1: (a) AMS 800 (Boston Scientific, Marlborough, MA, USA), image reproduced with permission from Boston Scientific. (b) ZSI 375 (ZEPHYR Surgical Implants, Geneva, Switzerland). (c) FlowSecure (Sphinx Medical, Bellshill, North Lanarkshire, United Kingdom). (d) Periurethral Constrictor (Silimed, Rio de Janeiro, Brazil).|
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Urethral erosion has shown to occur in up to 8.5% (3.3%–27.8%) of implants. Although cuff erosions are commonly reported in the literature when discussing AUS, there are little data on the timing and etiology of urethral erosions.
Urethral erosions seem to occur more frequently within the first 2 years of implantation, with subsequent decreasing incidence over time, and there are three main hypotheses for the mechanism of cuff erosion. For patients who experience urethral cuff erosion within 1 year, it is hypothesized that urethral injury or shallow dissection at the time of implantation may account for early erosion. For patients that present with later erosions, a consideration would be poor urethral tissues, which can be contributed by comorbidities, such as previous radiation or diabetes. The poor urethral tissue undergoes atrophy or necrosis, and this eventually results in erosion of the cuff. The final mechanism would be inappropriate or traumatic catheterization, especially by health-care providers that may not be aware of the AUS.
Management of urethral erosion is usually immediate removal of the AUS and subsequent urinary catheter placement. A case report reviewed the management of two cases with urethral erosion that were treated nonsurgically. In these two cases, the implant remained functional with no infection or loss of continence and decision to avoid explantation was refusal by the patients and should not be considered a standard of care. Subsequent reimplantation of AUS can be considered if the patient is still keen for intervention.
Common sequelae of cuff erosion are urethral strictures. The rates of between 8.3% and 32%, have been quoted for patients who have had AUS cuff erosions. Several retrospective trials have described urethroplasty postexplantation and subsequent AUS reimplantation; however, up to 36% of patients had subsequent cuff complications, including early erosion and pump migration. For urethral strictures postcomplete AUS cuff erosion, management seems to follow that of traumatic urethral injuries, with dense, full-thickness scar formation. In these patients, delayed anastomotic urethroplasty may have success rates of up to 86%.
Following cuff explantation, there is debate regarding explantation of the PRB that is located in the deep pelvis. A retrospective analysis of retained PRBs after the removal of infected or eroded cuffs suggested that up to 75% of patients can be managed conservatively, with the median time to PRB removal due to infection being 4 months.
SUI recurrence during follow-up of a functioning AUS is typically presumed to be due to urethral atrophy. The common presumed pathophysiology underlying urethral atrophy is urethral tissue hypoxia, which is secondary to long-standing pressure from the cuff on the urethral wall. A systematic review published in 2012 reported the mean pooled incidence of urethral atrophy as 7.9%. To date, this is the largest systematic review of long-term outcomes following AUS insertion in patients with nonneurogenic SUI. Only three studies gathered were prospective trials. The main indicator of success was continence, which was defined as no pad or 1 pad per day. However, current knowledge regarding urethral atrophy is still limited and further studies are needed to define urethral atrophy and assess the rate of urethral atrophy.
A recent prospective trial hypothesized that the entity of urethral atrophy may not be clinically significant. There is currently no standardized definition for urethral atrophy and is usually diagnosed intraoperatively from the characteristic waisted appearance of the urethra when the cuff is removed. Fifty consecutive patients underwent exploration and reimplantation for malfunctioning AUS. In 19 patients, no obvious cause was found in the device; nonetheless, when the explanted implants were challenged with manometry, it was found that there was loss of pressure in all instances. Replacement of the entire explanted AUS after capsulotomy with an identical cuff size and PRB was successful for the patients, in which no obvious abnormality was found (defined as totally dry or “socially dry,” i.e., no more than 1 pad per day) in 85.7% of cases. However, this is a small study, with no histological results or control arm.
| Management of Urethral Atrophy|| |
In general, four main methods have been described when managing urethral atrophy in patients who have recurrent SUI despite a functioning AUS. They involve cuff downsizing, the placement of a second cuff or “tandem cuff placement,” cuff repositioning or transcorporal cuff placement, and changing PRBs to higher pressure ranges.
The aim of all these maneuvers is still to achieve continence for patients by reestablishing coaptation of the urethra by the AUS.
Cuff downsizing involves removing the existing cuff and replacing it with a smaller sized cuff within the established false capsule. Early retrospective studies showed that severe leakage episodes decreased and patient satisfaction increased after urethral cuffs were downsized. Many advocate downsizing cuffs to 4- or 3.5-cm cuffs, with good results. However, there are two main problems with cuff downsizing. As the pathophysiology of urethral atrophy is proposed to be secondary to pressure necrosis and hypoxia of urethral tissues, the use of smaller cuff sizes will likely lead to worsening atrophy or possibly erosion. Brant et al. recently reported that the use of a 3.5-cm cuff is a predictor of cuff erosion. While these were considered novel findings, this study was done shortly after the 3.5-cm cuff became commercially available. The authors postulate that the higher incidence of erosion may not be an inherent flaw of the device, but rather selection bias, as smaller cuffs may be sized for smaller urethras that are compromised and incapable of supporting an AUS. Conversely, Loh-Doyle et al. showed that the 3.5-cm cuff was an independent risk factor for component failure, even after its initial commercial introduction. Therefore, it is difficult to attribute the negative results simply to its new market availability. Patients must be counseled accordingly and weigh the benefits against the additional risk erosion that comes with cuff downsizing.
Transcorporal cuff placement or cuff repositioning
Transcorporal cuff placement or cuff repositioning has also been proposed as a salvage treatment for failed AUS due to urethral atrophy. The underlying concept of transcorporal AUS placement is to increase the healthy tissue bulk between the cuff and the urethral body. By placing the urethral cuff through the corpora cavernosa, this configures the tunica albuginea between the cuff and the urethra, while simultaneously avoiding further urethral dissection. The use of transcorporal AUS has previously been described as an effective salvage method for AUS that requires revision from either urethral atrophy or erosion, and its use has even been investigated as a primary intervention with no prior urethral surgery [Figure 2].,
|Figure 2: (a) Single transcorporal cuff on distal bulbar urethra placed in tandem with existing periurethral cuff on proximal bulbar urethra. (b) Two transcorporal cuffs placed on the proximal and distal bulbar urethra. (Images reproduced with permission from Dr. Daniel Elliott, Mayo Clinic, MN, USA).|
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The use of transcorporal AUS has also been investigated in patients that may potentially have poorer urethral tissues, such as patients with previous radiation. A retrospective analysis of 44 patients showed that the social continence rate was 69.7%; however, overall complications were up to 45.9%. Subgroup analysis showed that patients with previous radiation had less AUS complications than those with previous urethral surgery.
The largest prospective trial included 23 patients that underwent transcorporal cuff placement after urethral atrophy or erosion or a previous AUS or male sling. Seventy-six percent of patients were found to be dry or socially dry, with 1 or fewer pads daily, with high patient satisfaction. In another study, continence rate at 45 months, defined as 0–1 pad daily, was 80%, with a reoperation rate of 37.5%. Good erectile function has also been observed postsurgery, with those patients who were potent and able to maintain their sexual function. However, many of these patients start out with existing erectile dysfunction, and due to small numbers in all published data, it is difficult to ascertain whether transcorporal cuff placement would really impact the sexual function.
Proximal urethral cuff repositioning has also been described in the treatment of urethral atrophy. This involves removal of the old cuff from the false capsule with subsequent mobilization of urethra proximal to the previous sphincter site. This is based on the assumption that previous cuff location was likely suboptimal, and should be at the thickest part of the bulbar urethra, which is usually more proximal, thick, and robust. By mobilizing the urethra proximal to the existing pseudocapsule, this allows visualization of the most proximal aspect of the bulbar urethra, allowing proper replacement of the cuff. In six patients, five patients attained social continence (defined as none or 1 pad per day) with repositioning of the urethral cuff and no patient required revision at median 1-year follow-up.
Tandem cuff placement
Tandem cuff placement involves implantation of a second cuff, usually distal to the existing cuff, on the background of recurrent SUI post-AUS insertion. The concept behind tandem cuff placement is that the initial cuff provides little to no coaptation. A second cuff placed distally allows urethral compression and reestablishes continence.
The use of tandem cuff placement in the role of severe incontinence has also been investigated both as a primary intervention and as salvage treatment of failed AUS. As a primary treatment, tandem cuff placement has not shown to be superior in dry rate and overall incontinence, yet is associated with additional complications that require surgical revision (55% of tandem cuff patients as opposed to 28% of single cuff patients). Complications included urethral stricture, mechanical failure, erosion, and rectourethral fistula. The authors hypothesize that ischemia due to the tandem cuffs may have contributed to at least 7 of the 12 double-cuff patients that underwent revision. Thus, tandem cuff placement as an index treatment for SUI should not be considered.
However, tandem cuff placement has been shown to improve incontinence rates for failed AUS. Usually, the existing bulbar urethral cuff is left in situ and a second distal cuff is placed transcorporally., However, both cuffs can also be placed transcorporally after explantation of the original bulbar urethral cuff. This technique is usually reserved for the most difficult salvage cases, especially those that have experienced previous infection or erosion. Continence rates posttandem cuff placement range from 56% to 69% with high patient satisfaction. Reoperation rate for tandem cuff placement ranges from 16% to 22%.
When compared to cuff downsizing, tandem cuff placement has been shown to be equivalent to single-cuff downsizing when treating urethral atrophy in device survival rates. Median time to primary failure was 6.13 years (single cuff) versus 4.92 years (tandem cuff) (P = 0.53), with similar demographic groups. Subgroup analysis of the tandem cuff group revealed that those patients who underwent transcorporal cuff placement experienced a shorter 3-year device survival rate (44% vs 80%, P = 0.0016) when compared to their nontranscorporal approach cohort. However, Linder et al. were not able to ascertain functional outcomes as it was a retrospective study. Significantly, there are no large prospective studies that compare cuff downsizing to tandem cuff placement in the treatment of urethral atrophy.
Replacement of PRBs
Although more difficult to revise, replacement of the PRB has been described in the management of recurrent SUI after AUS implantation. This technique is usually used when there is recurrent incontinence in the absence of urethral erosion or obvious mechanical failure of any of the AUS components.
The rationale behind this technique is that the higher pressures in the PRB will help urethral coaptation and the reestablishment of continence. It also has the further benefit of leaving working components of the AUS (cuff and pump) undisturbed in their existing locations, hopefully reducing the chance of erosions or migration. A retrospective study comparing PRB replacement to cuff replacement found that reintervention rates following PRB revision compared to cuff revision were similar (44.8% vs 46.7%). However, due to the difficulty of isolated PRB replacement, the authors concede that this technique has become less favorable compared to wholesale change of the device.
| Conclusion|| |
AUS continues to be the gold standard in the treatment of moderate-to-severe nonneurogenic SUI. As the complication rate continues to decrease with surgeon experience, counseling for reoperation for AUS still remains a pillar of patient awareness, no matter the etiology of the revision. Amidst the data available, there are several salvage techniques that are well documented when attempting to treat AUS complications. However, more prospective trials are needed to define urethral atrophy and assess the risk factors of future AUS complications. Determining the best salvage treatment with robust randomized controlled trials presents an even greater obstacle for clinicians in the future due to the small number of patients.
| Author Contributions|| |
NHH performed the literature review and drafted the manuscript. RBWT conceived the study and provided guidance on the manuscript. Both authors read and approved the final manuscript.
| Competing Interests|| |
Both authors declared no competing interests.
| Acknowledgments|| |
We would like to acknowledge Dr. Daniel Elliott (Department of Urology, Mayo Clinic, Rochester, MN, USA) for the use of his images.
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[Figure 1], [Figure 2]