Artificial urinary sphincter

The 'gold standard' therapy for sphincteric incontinence in the male is the AMS 800 (American Medical Systems, Minne-tonka, MN) artificial urinary sphincter prosthesis (Fig. 34.2). Of the available options, this device offers the greatest chance of cure from sphincteric incontinence. Previous models of the artificial urinary sphincter had considerable technical problems, including a high rate of urethral erosion.90 The introduction of the narrow-backed urethral cuff in 1987 has resulted in fewer complications, including a decreased urethral atrophy rate and fewer urethral erosions without compromising mechanical reliability91-93 (Fig. 34.3). Acceptable social continence can be expected in more than 90% of patients.94-96 Although perfect continence is not achieved in the majority of cases, significant improvement in quality of life is likely following implantation of the AMS 800.97,98 Long-term reliability rates are good. Montague reported a reoperation rate of only 12% at a mean follow-up of more than 7 years in 113 patients.99 Other

Ray Images Prostate Cancer
Fig. 34.2. Plain anterioposterior X-ray demonstrating the location of the reservior (black arrow) and cuff (white arrow) of an AMS 800 artificial sphincter.
Revision Urinary Sphincter
Fig. 34.3. Components of the AMS artificial urinary sphincter. At the top is the reservoir, in the middle the control pump and the lower component is the urethral cuff.

long-term series report overall revision rates for all causes of failure (infection, erosion, atrophy, etc.) as between 21% and 33%.91'94'97'100-102 Urethral atrophy is the most common reason for revision of the artificial sphincter103 but the dreaded complications of erosion or infection can occur in up to 1-12% of patients95,101 (Fig. 34.4).

The most significant adverse factor in implanting the AMS 800 prosthesis is a prior history of external beam radiotherapy.95,103-105 These patients are at greater risk for urethral erosion and urethral atrophy. Nevertheless, successful implantation can be achieved in greater than 90% of these patients.103'106 Routine deactivation of the device at night has been recommended to decrease the reoperation rate95 but controlled studies supporting this recommendation are lacking. Urethral catheterization, especially traumatic urethral catheterization following AMS 800 implantation is also associated

Aus 800 Pump Location
Fig. 34.4. Infection of the AMS 800 sphincter characterized by erythema, edema and swelling of the scrotum and perineum.

with urethral cuff erosion.105 Interestingly, prior intraurethral collagen injection does not appear to decrease the success or long-term durability of the AMS 800.107

Recurrent incontinence following implantation of the AMS 800 may have several etiologies and a careful evaluation is necessary. Bladder factors, including new onset detrusor overactivity should always be considered and can be diagnosed by a well-performed urodynamic evaluation. Urethral erosion and/or mechanical malfunction, including fluid leak, may result in the sudden reappearance of incontinence. Cystoscopy, voiding cystourethrography (Fig. 34.5) or video urodynamics may be helpful in assessing for these possibilities. Urethral atrophy may present with slowly increasing incontinence. Perfusion sphincterometry is a simple low-cost

Urinary Ams 800

Fig. 34.5. Films during a cystogram in evaluation recurrent incontinence following AMS 800 implantation. No extravasation of contrast is seen to suggest urethral erosion. In the upper image, in the activated state, the column of contrast in the urethra stops at the level of the urethral cuff (black arrow). There appears to be contrast distal to the cuff, which represents the filling catheter. In the lower image, when the device is deactivated, contrast is seen to flow through the cuff (white arrow). Urodynamic evaluation revealed an overactive bladder as the cause of the recurrent incontinence.

Fig. 34.5. Films during a cystogram in evaluation recurrent incontinence following AMS 800 implantation. No extravasation of contrast is seen to suggest urethral erosion. In the upper image, in the activated state, the column of contrast in the urethra stops at the level of the urethral cuff (black arrow). There appears to be contrast distal to the cuff, which represents the filling catheter. In the lower image, when the device is deactivated, contrast is seen to flow through the cuff (white arrow). Urodynamic evaluation revealed an overactive bladder as the cause of the recurrent incontinence.

Bilder William Godward

method that can be utilized to assess for cuff atrophy.108 The options for treatment for urethral atrophy include placement of a tandem cuff,109'110 downsizing the cuff, relocating the cuff more proximally111 or changing to a higher pressure reservoir.

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