The Artificial Urinary Sphincter

ANGELO E. GOUSSE

HARI S. G. R. TUNUGUNTLA

NEAL PATEL

IZAK FAIENA

INTRODUCTION AND EPIDEMIOLOGY

Normal lower urinary tract function is critical in maintaining urinary continence at low bladder pressure. Up to 16 to 20 million Americans have some type of urinary incontinence with potential major psychosocial consequences. Urinary incontinence is prevalent in men, although the overall numbers are lower than in women. The Epidemiology of Lower Urinary Tract Symptoms (EpiLUTS) study examined rates of urinary incontinence in both men and women in the United States, United Kingdom, and Sweden (1). Prevalence of any urinary incontinence was as high as 46% for men and 68% for women reporting urinary incontinence. However, this included various forms of urinary symptoms in addition to incontinence. When categorized by type, 5.6% of men reported urgency urinary incontinence only, 0.8% stress urinary incontinence only, 1.4% mixed urinary incontinence, 6.3% had urgency urinary incontinence and another form of urinary incontinence, and 1.2% had stress and another form of urinary incontinence.

Etiology for urinary incontinence includes neurologic disorders, iatrogenic following surgery on the lower urinary tract (e.g., radical prostatectomy and transurethral resection of the prostate), and bladder dysfunction. Urinary incontinence secondary to intrinsic sphincter dysfunction can potentially be cured by artificial urinary sphincter (AUS), an implantable prosthetic device consisting of a pressure-regulating balloon (PRB), a cuff and a pump mechanism (Figs. 45.1, 45.2 and 45.3). There are several choices of PRB including those with a preset pressure of 51 to 60, 61 to 70, or 71 to 80 cm H2O. Selection of the PRB is based on the location of the cuff. Although 61 to 70 cm H2O pressure balloon is the most commonly used PRB, a higher pressure (71 to 80 cm H2O) is sometimes used for recurrent stress urinary incontinence and when a bladder neck cuff is used. The cuff is available in sizes ranging from 3.5 to 5.5 cm, the selection of which depends on its location at the bulbar urethra versus bladder neck. The choice of cuff size needs a subtle calculation sometimes in that an additional 2 to 3 mm may be added to the measured urethral circumference to account for the inaccuracy in measuring the actual circumference at the insertion site. A smaller cuff becomes necessary in patients with recurrent incontinence following cuff atrophy. A 5.0-cm and sometimes 5.5-cm cuff may be used if it is inserted at bladder neck. The pump has a built-in deactivation button, manual pump, and delayed refill resistor. An activated cuff remains open for 2 to 4 minutes as fluid leaves the cuff, only to slowly return through the refill resistor in the pump, restoring continence. Transfer of fluid and the resultant transfer of pressure to the cuff is prevented by the deactivation button of the pump when this feature is used, thus leaving the device temporarily nonfunctional and the patient incontinent.

FIGURE 45.1 AUS with single cuff.

FIGURE 45.2 AUS with double cuff.

Since its first implantation by Brantley Scott in 1972 (2), the original model underwent several technical modifications and advances resulting in the current AUS implant. Notable advances in design include the narrow-backed cuff (1987) (3) to limit urethral erosion and color-coded kink-resistant tubing assuring secure device assembly and function. It was recently reported that learning curve for AUS placement was found to be approximately 25 cases based on complications and reoperation rates (4).

FIGURE 45.3 AUS with InhibiZone-coated cuff and control pump.

DIAGNOSIS

Identifying the source and type of the incontinence is the first step in determining the need for an AUS. Diagnosis of the etiology of incontinence can be determined using multichannel urodynamic testing such as videourodynamic studies. Such studies assess the intrinsic sphincter function, bladder capacity, and detrusor compliance as well as evaluate for detrusor overactivity and leak point pressures. This evaluation is especially important in patients with neurogenic etiologies because AUS placement in some of these patients can have potentially detrimental long-term effects to renal function.

Along with urodynamic evaluation, cystoscopic examination must be performed to evaluate the quality and health of the urethral tissue throughout, and especially at the level where an AUS is to be placed whether it is at the bladder neck or bulbar urethra. Most importantly, urethral stricture must be ruled out with cystoscopy.

A thorough physical exam should be performed. Specifically, a neurologic assessment is essential in determining patient eligibility for AUS placement. Traditionally, the pump is placed in the right hemiscrotum in a right-handed patient and on the left side in a left-handed patient. During physical exam, it is of paramount importance to confirm that the patient has the required manual dexterity, pincer grip, and finger strength necessary for the day-to-day manipulation of the pump to achieve satisfactory voiding. Evaluation of the genitalia is also important in identifying integumentary and microbial issues that may prevent placement of AUS. Sites of planned incisions must be examined carefully to assess for viability and integrity of the skin because this is important in operative planning and placement eligibility.

INDICATIONS FOR SURGERY

Indications for Artificial Urinary Sphincter Placement

Postprostatectomy incontinence due to intrinsic sphincter dysfunction is the most common indication for an AUS. Other indications include posterior urethral trauma leading to incompetent sphincter; persistent female incontinence refractory to all other incontinence therapies; and congenital abnormalities leading to persistent incontinence such as exstrophy-epispadias complex, spina bifida, and various other genitourinary abnormalities.

Contraindications for Artificial Urinary Sphincter Placement

As mentioned earlier, a key physical exam assessment is the patient’s neurologic status. AUS is absolutely contraindicated in patients with physical and/or mental disability whose conditions are severe enough to render them noncompliant and/or unreliable regarding management and use of the device.

Relative contraindications include female patients with prior history of pelvic radiation because they are at higher risk for erosion (both urethral and vaginal). Also included are patients with progressive neuromuscular disorders who may initially be deemed fit to use the device properly in the short term but will likely be unable to use the device in the long term. Lastly, patients with uncontrolled detrusor overactivity, noncompliant bladders, and/or small bladder capacity are also relatively contraindicated.

ALTERNATIVE THERAPIES

Given lack of sphincter function, aside from AUS placement, the patient may consider urethral bulking agents, bladder neck closure, male urethral sling placement, and/or urinary diversion. Selection of urethral sling versus AUS based on the measured Valsalva leak point pressure (e.g., AUS for very low leak point pressures of <40 cm H₂O pressure and sling for patients with moderate leak point pressures of 50 to 70 cm H₂O pressure) is a contentious issue. However, male urethral sling may be an option in patients with cystoscopically documented residual sphincter function, partial coaptation of the sphincteric urethra, and absence of any sectoral defects in the external urethral sphincter (Table 45.1).

SURGICAL TECHNIQUE

Preoperative Preparation

Infection of an implanted AUS device can have long-term detrimental effects for the patient. Therefore, it is important to be prudent regarding potentially modifiable preoperative and postoperative factors which may affect risk of infection. In a recent contemporary series, Staphylococcus aureus was the most common causative agent for AUS infection (5).

Preventive strategies must be employed to ensure the patient has the best chance for an infection-free outcome. Patients with urinary tract infections must be treated prior to surgery. Skin infections or irritation and breakdown in the area of the genitalia and planned incision sites must be addressed, and preventive measures must be taken in the perioperative period to prevent recurrences during the tissue healing process. If the genital skin involvement is secondary to urinary leakage, preoperative indwelling urethral or suprapubic
catheter placement facilitates healing of the skin. Because catheters are potential sources for urinary tract infections, it is recommended removing catheter placed for this reason about 1 week prior to AUS implantation. If the patient had a catheter or intermittently catheterizes, prophylactic antibiotics may be considered starting a few days prior to the procedure.

TABLE 45.1 OUTCOMES OF INFLATABLE PENILE PROSTHESIS (IPP) VERSUS ARTIFICIAL URINARY SPHINCTER (AUS)/MALE SLINGS

			IPP device	No. of Patients	Follow-up (months)	SHIM/function	Post-op pad use
IPP and males slings		SUI device
	Rhee et al., 2005	InVance	AMS700	4	15	NA/satisfactory	0 (100%)
	Gorbatiy et al., 2010	InVance/advance	AMS700	8 (3/5)	13.6	23.5	1 (100%)
IPP and AUS		AUS type
	Parulkar et al., 1989	AMS792/800	Various	40	35.7	NA/98% functional	0-1 (90%)
	Wilson et al., 2003	AMS800	NA	12	12	NA	0-1 (100%)
	Seller et al., 2004	AMS800	AMS700CX	15	16	NA	NA
	Kendirci et al., 2006	AMS800	AMS700CX	22	17	NA	0-1 (100%)
	Mancini et al., 2007	AMS800	AMS700CX	33	21.6	NA/97% functional	0-1 (72.7%)
Abbreviations: AMS (American medical systems, Minnetonka, MN, USA); AUS, artificial urinary sphincter; IPP, inflatable penile prosthesis; SHIM, sexual health inventory for men; SUI, stress urinary incontinence. Reprinted with permission from Amend B, Toomey P, Sievert KD. Artificial sphincter. Curr Opin Urol 2013;23(6):520-527. Copyright © 2013 Wolters Kluwer Health.

Preoperative antibiotics that cover both aerobic and anaerobic organisms should be given approximately 1 hour before surgery or at time of induction. Antibiotic choice must have broad enough coverage for both skin and genitourinary flora.

Patient preparation also includes on-table shaving; patients must be instructed not to shave prior to arriving to the hospital on the day of the procedure. Shaving immediately prior to the start of the operation will reduce the chance of infection.

A recent randomized controlled trial evaluating the efficacy of chlorhexidine versus povidone-iodine-based antimicrobial scrubs in patients undergoing genitourinary prosthesis placement found that chlorhexidine prep was superior to povidone-iodine prep regarding positive postpreparation cultures of 8% versus 32%, respectively. They also concluded that there was no significant difference in urethral or genital skin irritation among the two skin preps. Chlorhexidine required a 2-minute prep time versus 5-minute prep time for povidone-iodine. Overall, this study found chlorhexidine to be a superior agent (6). The authors did not report any significant difference in the incidence of clinical complications between the two groups.

After anesthesia is induced and the patient has been shaved, the patient should be positioned in a dorsal lithotomy position and after being prepped should be draped in a such way to allow the surgeon access to both the perineum, genitalia, and suprapubic and lower abdominal area. Next, a 16Fr urethral catheter should be placed. Betadine mixed with normal saline is instilled in the urethra prior to the insertion of the urethral catheter because this is colonized in some patients.

ARTIFICIAL URINARY SPHINCTER PLACEMENT IN MEN

Perineal Cuff Placement

In men, proximal bulbar urethral cuff placement is optimal. For cuff placement around the bulbous urethra, a midline perineal incision should be made over the bulbar urethra. The incision should allow for dissection and exposure of approximately 2 cm length of urethra (Fig. 45.4). Great care must be taken in handling the corpus spongiosum, and every measure should be taken to prevent inadvertent entry into the urethral lumen. Electrocautery should be avoided in controlling bleeding associated with injuries to corpus spongiosum, which should be repaired with absorbable (4-0) suture instead.

The urethral mobilization should be carried out circumferentially by freeing the attachments of the dorsal aspect of the urethra from its adjacently associated corpora. Once the urethra is freely mobilized, the circumference can be accurately determined using the sizer/measuring tool provided in the AUS surgical kit. When placing the sphincter, the cuff size should be such that it is neither too tight nor too loose. One of the hints to ensure determine appropriate cuff size is that one should be able to easily insert the closed jaws of a right-angle clamp between the urethra and the sizer/cuff. It is important to select the cuff about 2 to 3 mm longer than the measured size to prevent a tight fitting cuff over the urethra, thereby preventing possible erosion. Usually, the most common size for a man undergoing a bulbar urethra AUS implant is 4.0 to 4.5 cm. More recently, 3.5-cm cuffs are starting to gain favor for both primary and revision AUS placement (7).

After the cuff is placed, a 4- to 5-cm incision is made 2 to 3 cm above and just lateral to the pubic symphysis. This will be the planned reservoir (PRB) site. A transverse incision is then made in the fascia followed by blunt dissection to develop a space for the reservoir (PRB) between the transversalis fascia and

the retropubic space. The PRB is then placed in the space developed and inflated to 23 to 25 mL. Intraperitoneal placement of the PRB is not recommended because the PRB is functional only in the relatively closed retropubic space (personal communication, December 2014, American Medical Systems, Minnetonka, Minnesota). The type of the PRB chosen (61 to 70 cm H2O pressure versus 51 to 60 cm H2O pressure) depends on the indication for AUS placement. PRB with a higher pressure (71 to 80 cm H₂O) may be used with a bladder neck cuff. If AUS placement is for postprostatectomy incontinence, then a 61- to 70-cm H2O pressure PRB is acceptable. If the patient has any condition that may increase the chance of atrophy or erosion (such as prior radiation), a lower pressure PRB (51 to 60 cm of H2O pressure) is indicated. The tubing from the cuff will need to be passed into the suprapubic incision to be connected to the reservoir.

FIGURE 45.4 Various steps depicting perineal cuff placement in men. A: Perineal skin incision. B: Exposure of corpus spongiosum of the bulbar urethra after incising bulbospongiosus muscle. C: Circumferential mobilization of bulbar urethra. D: Measurement of the circumference of the bulbar urethra to select the appropriate cuff size. E: Appropriate size cuff placed around the proximal bulbar urethra. F: Clear and black tubing of the AMS 800. G: Filling of the reservoir with the “filling solution”. H: Subcuticular closure of the perineal skin incision.

Next, the control pump is placed in the subdartos pouch that is developed by spreading the ring clamp. The pump is placed in the right hemiscrotum in a right-handed person and vice versa. It is placed in the most anterior and dependent portion of the scrotum superficial enough with the deactivation button easily palpable. A path for the pump tubing is developed superiorly from the suprapubic incision into the perineal incision using a long clamp. It is important to secure the pump through the scrotal skin with a Babcock clamp to allow for optimal pump positioning while providing adequate tubing length until the end of the procedure.

Once all the tubing has been passed, excess tubing should be cut away and the remaining tubing should be connected using the connectors provided in the AUS accessory kit. Once all the tubing has been connected, the system should be cycled to test pump function. During the test, the urethral catheter should be removed, and urethroscopy should be used to visualize the cuff to assess for degree of occlusion of the activated cuff. Once the surgeon is satisfied, the cuff should be deactivated and remain deactivated for 4 to 6 weeks to allow for proper healing. Each layer of the wound is closed with absorbable sutures. The urethral catheter need not be reinserted unless there is suspicion regarding inadequate bladder emptying. The patient should be made aware that their incontinence will persist until the AUS is activated after an appropriate healing period. Patients can usually be discharged home 2 to 3 hours after surgery or on the first postoperative day with a 5- to7-day course of an oral antibiotic. The device is traditionally activated 6 weeks following implantation.

Transcorporeal Cuff Placement

This approach is usually reserved for patients who have had prior urethral erosion and/or an anatomically suboptimal urethra secondary to prior infected AUS or severe atrophy. Raj et al. (8) noted that comorbidities such as hypertension, coronary artery disease, and prior radiation predisposed the patient to a higher chance of erosion. Given that a more proximal placement of an AUS is sometimes not feasible, a more distal approach has been evaluated but not without its own set of challenges. Wall thickness of the corpus spongiosum of the urethra becomes an issue, as it becomes thinner distal to the bulbar urethra, putting the urethra at a higher risk of erosion.

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