Erosions of the artificial urinary sphincter: risk factors, outcomes and management

boxed-textRaj GV et al. (2006) Outcomes following erosions of the artificial urinary sphincter. J Urol 175: 2186–2190

Box 1: Practice point

This study alerts surgeons who perform artificial urinary sphincter implantation of risk factors associated with erosion, and proposes guidelines to improve successful revision surgery

Synopsis

Background

Although the artificial urinary sphincter (AUS) provides excellent long-term outcomes and patient satisfaction in men with urinary incontinence, urethral cuff erosion arises in up to 5% of cases, presenting complex management problems with respect to reimplantation.

Objective

To examine the operative management and outcomes of patients with urethral cuff erosions and to assess any preoperative risk factors for erosion.

Design

This was a retrospective review of the medical records of patients who had undergone primary and secondary bulbar urethral AUS implantations and revision surgeries using the AMS 800^® (AMS Research Corporation, West Minnetonka, MI) hydraulic artificial urinary sphincter at a single center between January 1990 and September 2003.

Intervention

Patient records (medical and operative) were reviewed and a range of demographic, medical and surgical variables were recorded. All patients included in this analysis had been treated by a single surgeon, minimizing the potential confounding influence of different surgical techniques.

Outcome measures

Surgical postoperative measures included functional continence, durability of implant, sphincter function and length of follow-up. Demographic and surgical variables of patients with and without erosions were compared.

Results

A total of 637 records were reviewed. Of these, 46 patients who underwent a total of 54 explantations of the AUS device for erosions at a median follow-up of 28 months formed the study cohort. Analysis showed that there was an increase over time in the number of revision surgeries for AUS cuff erosions and a decrease in revision surgeries for mechanical malfunctions. Of the risk factors investigated, hypertension (P = 0.006), coronary artery disease (P = 0.03), prior radiation therapy (P = 0.006) and prior AUS revision surgeries (P = 0.0001) were found to be associated with the likelihood of erosions. The majority of patients (57%) who underwent a second AUS implantation because of erosion had good outcome in terms of continence (0–1 pad daily); persistent moderate incontinence (1–3 pads daily) was present in 17% and severe (>3 pads daily) in 12% of patients. Overall, however, continence rates were significantly lower in patients undergoing revision surgery for erosion than in those undergoing revision surgery for other causes (P = 0.0001). The 5-year durability of reimplantation for AUS cuff erosions was only 60%, significantly worse than that for patients undergoing urethral revision surgeons for other causes (P = 0.0001). Patients who underwent revision surgery for erosion were also more prone to further erosions (34%) within an average of 6.7 months (range 3–24 months).

Conclusion

Patients with comorbidities, including hypertension, coronary artery disease, prior radiation therapy and prior AUS revision surgeries, are more likely to suffer from erosions of their AUS. The use of salvage strategies at revision surgery can, however, restore continence in a significant proportion of these patients.

Commentary

Ever since Scott introduced the AUS, erosions and infections continue to be the 'sword of Damocles' that hangs over surgeons and implant recipients throughout the life of the AUS.¹ As such, practitioners and patients must exert all efforts and diligence to keep the sword from falling.

The complication of urethral erosion is a devastating outcome; the patient will need at least two operations (removal and reimplantation) and there is an increased risk of subsequent failure. In this study, Raj et al. provide excellent guidelines to reduce revision-surgery failures, including seeking alternative urethral sites, selecting proper cuff size, having a meticulous sterile technique, waiting for complete urethral healing, and consideration for nocturnal deactivation.

The authors report that the risk factors associated with urethral erosion of the AUS cuff are hypertension, coronary artery disease and radiation therapy; however, the event that led to the diagnosis of urethral erosion was not reported. The authors suggest that hypertension and coronary artery disease might be associated with vascular insufficiency, predisposing patients to tissue breakdown and urethral cuff erosion, but in my experience many erosions are not spontaneous. Rather, external trauma, or iatrogenic ischemia secondary to insertion of an indwelling catheter without deactivating the cuff in the open position, is a common culprit. An erosion can manifest immediately or days or weeks later, so these events might not be identified as factors contributing to the erosion.

Comorbidities can predispose patients to urethral erosion by increasing their chances of acute hospitalization and the need for indwelling catheterization. This might explain why the study found hypertension and coronary artery disease to be highly associated with erosion. Likewise, patients undergoing radiation therapy—another risk factor identified in the study—are prone to obstructions and retention that could require indwelling catheterization.

We have reported examples of AUS recipients who developed urethral erosions after prolonged indwelling catheterization without deactivating the cuff.² Such a maneuver leads to iatrogenic ischemia of the urethral wall that is sandwiched between the catheter and the inflated cuff. The erosion is often not recognized until well after the crisis has passed and the catheter has been withdrawn.

This paper helps us identify high-risk candidates for AUS implantation; however, for many of these men, AUS is the best solution. We believe that, as more patients with comorbidities are undergoing AUS implantation, it is imperative that we educate the patient, their family, and the nursing and medical staff about the need for attention prior to insertion of a urethral catheter. For an in-and-out catheterization, deflating the cuff just prior to insertion and removal of the urethral catheter is sufficient, but for insertion of an indwelling catheter, the AUS must be deactivated with the cuff open.