Artificial Urinary SphincterLast
Updated: September 17, 2004
|Synonyms and related keywords: AUS, AMS
800, incontinence, stress incontinence, urge incontinence,
overactive bladder, post-prostatectomy incontinence, stress urinary
incontinence, urinary sphincter, type III stress urinary
incontinence, intrinsic sphincter deficiency, ISD, incompetent
|Author: Jong M Choe, MD, FACS, Director of
Continence and Urodynamic Center, Assistant Professor, Department of
Surgery; Division of Urology, University of Cincinnati
|Jong M Choe, MD, FACS, is a member of the following medical
societies: American Association of University Professors, American
College of Surgeons, American Medical Association, American
Urological Association, International Continence Society, Ohio
Urological Society, and Society of University Surgeons
|Editor(s): Edward David Kim, MD, Associate
Professor, Department of Urology, University of Tennessee School of
Medicine; Francisco Talavera, PharmD, PhD, Senior
Pharmacy Editor, Pharmacy, eMedicine; Shlomo Raz,
MD, Professor, Department of Surgery, Division of Urology,
University of California at Los Angeles School of Medicine;
J Stuart Wolf, Jr, MD, Director of Michigan Center
for Minimally Invasive Urology, Associate Professor, Department of
Urology, University of Michigan Medical Center; and Stephen
W Leslie, MD, FACS, Founder and Medical Director, Lorain
Kidney Stone Research Center, Clinical Assistant Professor,
Department of Urology, Medical College of Ohio |
A biological urinary sphincter prevents
urinary flow by mucosal coaptation, compression, and pressure
transmission. An artificial urinary sphincter (ie, AMS 800) mimics the
biological urinary sphincter by providing a competent bladder outlet
during urinary storage and an open unobstructed outlet to permit voluntary
An artificial urinary sphincter is the only device that most closely
simulates the function of a biological urinary sphincter. Recent advances
in mechanical design, applications of new technology, and lessons learned
from clinical experience have inspired notable improvements.
Novel and ingenious in technical design, the AMS 800 device has
restored the quality of life in thousands of patients plagued by stress
urinary incontinence. The AMS 800 prosthesis is the only reliable surgical
treatment that provides lasting cure rates for men who are incontinent
History of the Procedure:
Scott et al introduced the
first artificial urinary sphincter in 1973. Called the AS 721, it
consisted of a fluid reservoir, inflation pump, deflation pump, and an
inflatable cuff with 4 unidirectional valves. The fluid within the
sphincter components conveyed the hydraulic pressure to the cuff.
Unfortunately, it was mechanically unreliable and had high urethral
In 1974, a newer model (ie, AS 761) emerged. This model offered a
pressure-regulating balloon that allowed automatic cuff closure. This
pressure-regulating balloon provided a constant, predetermined pressure
within the hydraulic system so that pressure-volume relationship became
The AS 761 device was quickly modified into the AS 742 model. This
newer sphincter eliminated the need for an inflation pump. The
pressure-regulating balloon functioned as a reservoir for cuff fluid. A
delay-fill resistor allowed enough time for the patient to void to
completion before the urethral cuff closed. However, this prosthesis still
was not ideal for patient use.
Introduced in 1979, the AS 791/792 device featured a control assembly
that merged the valves and the resistor into a single unit. Surgical
implantation was easier with fewer components and less connections.
However, the control pump did not have “on-off” capability. The risk of
urethral atrophy and cuff erosion remained high. A second operation was
required for activation of this device.
Through continued evolution and improvement, the AMS 800 device was
introduced in 1983. During the modification process, the control assembly
(ie, valves and resistor) was moved into the pump chamber. This model
featured a new locking mechanism that allowed the cuff to remain either in
open or in closed position; thus, the cuff could be left in a deflated
(open) state after implantation and could be activated 6-8 weeks later
without the need for a second operation.
Problem: An artificial urinary sphincter is reserved
for treatment of complex stress urinary incontinence—type III stress
urinary incontinence or intrinsic sphincter deficiency (ISD). Intrinsic
sphincteric dysfunction is the inability of the urethra to maintain
effective resting urethral closure pressure to keep the patient clinically
dry at rest and during periods of physical activity.
Etiology: Cases of intrinsic sphincteric dysfunction
involve men with a history of radical prostatectomy or transurethral
resection of the prostate (TURP); patients with myelomeningocele, previous
pelvic trauma, or history of pelvic radiation; and women with failed
The normal voiding cycle requires
that the urinary bladder and the sphincter work as a coordinated unit. The
urinary bladder has 2 functions: it relaxes to store urine and contracts
to eliminate urine. During urinary storage, the bladder is placid and acts
as a low-pressure reservoir. During voiding, the bladder actively
contracts to act as a pump. The urinary sphincter has 2 functions: it
contracts to store urine and it relaxes to eliminate urine. During urinary
storage, the urinary sphincter remains closed to prevent urine loss.
During urination, the urinary sphincter opens to allow unobstructed
Urinary incontinence results from a dysfunction of the bladder, the
sphincter, or a combination of both. Bladder overactivity causes urinary
frequency, urgency, and urge incontinence. Bladder underactivity causes
urinary retention. Sphincteric overactivity causes urinary retention.
Sphincteric underactivity results in stress incontinence. A combination of
bladder overactivity and sphincter underactivity results in mixed
incontinence—stress and urge.
Intrinsic sphincteric dysfunction, or type III stress incontinence, is
a complex form of stress incontinence whereby the urethra remains open at
all times. Risk factors for ISD include radical prostatectomy, TURP,
previous bladder neck surgeries, pelvic radiation, and neurologic
A common denominator of intrinsic sphincteric dysfunction is low
urethral resistance at rest and during periods of physical activity.
Whenever the intravesical pressure becomes greater than the urethral
resistance, stress incontinence ensues. A reliable method of restoring
continence is by artificially increasing the urethral resistance using an
implantable device such as an artificial urinary sphincter (ie, AMS 800).
The main criterion for implanting an artificial urinary sphincter is a
normal detrusor in a setting of intrinsic sphincteric dysfunction.
Clinical: Patients with ISD present with classic
history for stress urinary incontinence. They experience predictable loss
of urine whenever the intravesical pressure exceeds that of the urethral
pressure (eg, coughing, laughing, sneezing).
Often, these patients complain of involuntary urine loss when changing
their body position (eg, rising from sitting position). Women with ISD
experience more urine loss and require thicker pads compared to women with
For patients with pure ISD, symptoms of urinary frequency, urgency, and
nocturia typically are absent. However, when irritative voiding symptoms
also are present, coexisting overactive bladder should be suspected.
Candidates eligible for artificial
sphincter are those patients with type III stress urinary incontinence.
Essential characteristics of an ideal patient include highly motivated
personality, good manual dexterity, normal detrusor, absence of urinary
tract infection (UTI), and realistic expectations.
RELEVANT ANATOMY AND
Anatomy: The urethra is composed of an inner epithelial lining, a
spongy submucosa with rich vascular plexus, a middle smooth muscle layer,
and an outer layer of fibroelastic connective tissue. The spongy submucosa
is responsible for providing urethral occlusive pressure to create the
“washer effect.” The ability of the urethral mucosa to coapt to generate
an adequate urethral closing pressure is an important continence
mechanism. Urethral smooth muscle and fibroelastic connective tissues
serve to circumferentially augment the occlusive pressure generated by the
The urinary sphincter is composed of an internal sphincter and an
external sphincter. In females, the internal sphincter is composed of
bladder neck and proximal urethra. In males, the internal sphincter is
composed of bladder neck and prostate. Both males and females possess an
external sphincter known as the rhabdosphincter. The rhabdosphincter is
omega shaped and is composed of 2 types of striated muscle fibers, fast
twitch and slow twitch. Contraction of fast twitch fibers causes sudden
stopping of the urinary stream. This is known as the voluntary guarding
reflex. These fibers are responsible for allowing Kegel exercises. Slow
twitch fibers maintain the constant tonus of the external sphincter, which
is important in daily physical activities. This is known as the
involuntary guarding reflex.
Contraindications for artificial
urinary sphincter include UTI, detrusor hyperreflexia, small capacity
bladder, and poorly compliant detrusor. Preexisting UTI should be
eradicated prior to sphincter implantation. Hyperreflexic detrusor
generates high intravesical pressures that are transmitted to the upper
tracts and cause renal damage. Small bladders and decreased bladder
compliance should be managed by augmentation cystoplasty first. An
artificial urinary sphincter may be placed at the same time as
enterocystoplasty, or placement can be performed as a staged procedure.
Occasionally a patient may have expectations of being completely dry and
may not wish to deal with unforeseeable mechanical or surgical
complications. These patients have unrealistic expectations for the
operation as well as the device. Artificial urinary sphincters should not
be placed in patients with unrealistic expectations.
- Urinalysis and urine culture: The possibility of UTI should be ruled
out before implanting an artificial urinary sphincter. The presence of a
UTI is a contraindication to sphincter placement.
- Serum white blood cell count (WBC): Systemic leukocytosis should be
evaluated and treated prior to surgery.
- Serum creatinine: The patient should have normal renal function
prior to AMS 800 placement.
- This test is optional. This test can be used to assess bladder
neck and urethral function (ie, internal, external sphincter) during
the filling and voiding phases.
- Voiding cystourethrogram (VCUG) allows radiographic observation of
an incompetent bladder neck and coincident leakage during Valsalva
maneuvers. VCUG is performed most often at the time of
- Voiding diary: A voiding diary is a daily record of a patient's
bladder activity. The diary is an objective documentation of a patient's
voiding pattern, incontinent episodes, and any inciting events
associated with urinary incontinence. Although not critical, a properly
logged voiding diary may help influence diagnosis and therapy.
- Standing cough stress test: The patient stands upright with feet
shoulder width apart. Place a large towel under the patient's feet or a
small trash can between the patient's feet to catch the flow of urine.
Instruct the patient to perform the Valsalva maneuver and cough in
gradients (ie, mild, moderate, severe). Observable urine leakage in this
position constitutes a positive test result. If the bladder is empty at
the time of the Valsalva maneuver or cough, it will be a falsely
negative test result.
- Urodynamics is a means of evaluating the bladder capacity,
compliance, abdominal leak point pressure, the presence of phasic
contractions, and the pressure-flow relationship between the bladder
and the urethra.
- Simple urodynamics involves performing a noninvasive uroflow,
obtaining a postvoid residual (PVR) urine volume and a single channel
cystometrogram (CMG). A single channel CMG (simple CMG) is used to
assess the first sensation of filling, fullness, and urge. Bladder
compliance and the presence of uninhibited detrusor contractions (eg,
phasic contractions) can be noted during this filling CMG. A simple
CMG may be performed using water or gas (ie, carbon dioxide). Water is
the most common filling medium.
- Multichannel urodynamic studies are more complex than simple
urodynamics and can be used to obtain additional information,
including a noninvasive uroflow, PVR, filling CMG, abdominal leak
point pressure (ALPP), voiding CMG (pressure-flow), and electromyogram
(EMG). Water is the fluid medium used for multichannel
- The most sophisticated study is videourodynamics, which is the
leading standard in the evaluation of a patient with incontinence. In
this study, the following are obtained: noninvasive uroflow, PVR,
filling CMG, ALPP, voiding CMG (pressure-flow), EMG, static cystogram,
and VCUG. The fluid medium used for videourodynamics is radiographic
- Performing urodynamics
- Instruct the patient to arrive at the urodynamic laboratory with
a relatively full bladder. Note that patients with ISD have low
volume or empty bladder due to continuous incontinence. Perform a
noninvasive uroflow and PVR.
- Perform flexible cystoscopy. Survey the entire bladder
urothelium and then retroflex the cystoscope to examine the bladder
neck. Drain the bladder. Place a urodynamic urethral catheter,
rectal tube, and EMG electrodes.
- Rotate the patient to a standing position and equalize
transducers. Commence bladder filling using room temperature water
or contrast (Conray). Cold water may evoke false-positive detrusor
contractions (phasic contractions). Fill the bladder at medium rate
(eg, 60 mL/min). Assess the first sensation of filling, fullness,
and urge. Note bladder compliance and mark the presence of
uninhibited detrusor contractions.
- When the bladder fills to 250 mL, measure the ALPP. Instruct the
patient to perform the Valsalva in gradients (ie, mild, moderate,
severe) followed by cough (ie, mild, moderate, severe). Observe the
urine leakage fluoroscopically and by direct inspection.
- Following the ALPP measurements, finish the filling CMG to
completion. When the patient has a strong desire to void, perform a
voiding CMG (pressure-flow). At this point, note urodynamic
parameters, such as maximal flow rate (Qmax) and detrusor
pressure at maximal flow rate (PdetQmax).
- During the voiding CMG, note the activity of the EMG electrodes
and VCUG for possible detrusor sphincter dyssynergia (DSD). The
presence of DSD is confirmed by increases in EMG activity during
detrusor contraction or closure of the external sphincter on VCUG
- After the patient voids to completion, the videourodynamic study
is complete. The patient is informed about the findings on
urodynamic studies and is sent home on an oral
- Pad test: Patients with classic ISD present to the office with a
diaper or a pad in place. An adult male with a damp or wet pad inside
his underwear has urinary incontinence unless proven otherwise.
- Uroflow rate: The uroflow rate is a useful screening test used
mainly to evaluate bladder outlet obstruction. The uroflow rate is the
volume of urine voided per unit of time. Maximal flow rate
(Qmax) greater than 15 mL/s may be considered within the
reference range. Low uroflow rates (<15 mL/s) may reflect urethral
obstruction, a weak detrusor, or a combination of both. This test alone
cannot be used to distinguish between obstruction and an acontractile
detrusor. Patients with ISD demonstrate uroflow rates within the
reference range. A maximum flow rate (Qmax) of less than 15
cc/s with 150 mL of minimal void volume has been used to identify
patients with significant bladder outlet obstruction in drug study
trials (Ghormley, 1992; Lepor, 1990).
- Electromyography: Electromyography (EMG) helps to ascertain the
presence of coordinated or uncoordinated voiding. Failure of urethral
relaxation during a bladder contraction results in uncoordinated voiding
(ie, DSD). EMG is not necessary for evaluation of men who are
incontinent postprostatectomy; however, EMG is used in combination
during multichannel urodynamic studies.
- Postvoid residual urine volume: This measurement is a part of the
basic evaluation for urinary incontinence. Healthy men usually have a
PVR volume of less than 100 mL. If the PVR volume is high, the bladder
may be acontractile or the bladder outlet may be obstructed. Both of
these conditions cause urinary retention from overflow incontinence.
Patients with ISD have minimal postvoid residual urine.
- A filling cystometrogram (CMG) assesses the bladder capacity,
compliance, and the presence of phasic contractions. Most commonly,
liquid filling medium is used. An average adult bladder holds
approximately 450-500 mL of urine. During the test, provocative
maneuvers, such as coughing, handwashing, sitting on the commode for 1
full minute, and heel jouncing, may help to unveil bladder
- A filling cystometry may be performed in the following ways:
- Insert a catheter (connected to a special computer) into the
bladder for a single channel cystometry. Information recorded by the
computer is interpreted.
- Eyeball cystometry does not require special computers. Perform
bedside cystometry by inserting a catheter into the bladder and
hanging the irrigant bag at a predetermined height (eg, 100 cm
H2O) and observing the fluctuation of the meniscus within
the water chamber during uninhibited detrusor contractions.
- Eyeball cystometry using a flexible cystoscope is the same as
eyeball cystometry except that the flexible cystoscope acts as the
connection tubing. This allows simultaneous cystoscopy.
- Multichannel cystometry is a more sophisticated method of
measuring filling CMG where intravesical pressure (Pves),
intra-abdominal pressure (Pabd), detrusor pressure
(Pdet), and maximal flow rate (Qmax) are
- Voiding cystometrogram (pressure-flow study)
- A pressure-flow study simultaneously records the voiding detrusor
pressure and the rate of urinary flow. This is the only test that can
assess bladder contractility and the extent of a bladder outlet
obstruction. Pressure-flow studies can be combined with a voiding CMG
and videourodynamic study for complicated cases of
- Note that most adult men normally void with detrusor pressures
(Pdet Qmax) of 40-80 cm H2O. However,
pressures of 20-30 cm H2O or lower are considered to be
within the reference range if uroflow (Qmax) is within the
reference range or high (Blaivas, 1996).
- Abdominal leak point pressure
- Abdominal leak point pressure (ALPP) measurements allow clinicians
to classify stress urinary incontinence into type I, type II, and type
III, or type II and III in combination. ALPP of 0-60 cm H2O
is classified as type III stress urinary incontinence (ie, ISD). ALPP
of 60-90 cm H2O is classified as type II/III stress urinary
incontinence (ie, combination of urethral hypermobility and ISD). ALPP
of 90-120 cm H2O is classified as type II stress urinary
incontinence (ie, urethral hypermobility). ALPP greater than 120 cm
H2O is classified as type I stress urinary
- ALPP should be measured when the bladder is half full (eg, 250
mL), and both the Valsalva and coughing maneuvers should be performed.
Initially, instruct the patient to bear down in gradients (ie, mild,
moderate, severe), and then note the ALPP as the lowest intravesical
pressure (Pves) at which leakage is observed.
- If Valsalva maneuvers fail to produce the desired response,
instruct the patient to cough in gradients (ie, mild, moderate,
severe) to obtain the ALPP. The lowest intravesical pressure
(Pves) at which leakage is observed is the ALPP. The ALPP
obtained with Valsalva maneuver is more accurate than the
cough-induced ALPP. However, both techniques should be employed if
Valsalva maneuvers fail to manifest stress urinary
- Alternatively, both Valsalva and cough-induced ALPP may be
repeated by increasing the bladder volume in 100-mL gradients.
Increasing the bladder volume reportedly increases the sensitivity of
- Obtaining ALPP in male stress incontinence (ISD) is optional
because men with type III stress incontinence, by definition, have
ALPP less than 60 cm H2O.
- The precise role of cystoscopy in the evaluation of female urinary
incontinence is controversial because less than 2% of bladder tumors
have been identified by routine cystoscopy. However, cystoscopy allows
discovery of bladder lesions (eg, stitch in the bladder, bladder
cancer, bladder stone) that would remain undiagnosed by urodynamics
- In male urinary incontinence, cystoscopy should be performed more
routinely because a visual inspection of the urethra helps to
establish the presence of urethral stricture, vesical neck
contracture, or gross evidence of poor urethral coaptation and
- In general, cystoscopy also is indicated for patients reporting
persistent irritative voiding symptoms or hematuria. Obvious causes of
bladder overactivity, including cystitis, stone, and tumor, can be
diagnosed easily. This information is important in determining the
etiology of the incontinence and may influence treatment
- Videourodynamics combines the radiographic findings of VCUG and
multichannel urodynamics. Videourodynamics is the most sophisticated
diagnostic test for a patient with incontinence. Videourodynamics may
be used for evaluating any patient with lower urinary tract voiding
- In the absence of videourodynamics, the clinician may obtain
adequate information regarding male incontinence from (1) noninvasive
uroflow and PVR and (2) simple cystometry in combination with
Medical therapy: No known
reliable medical therapy for postprostatectomy male stress incontinence
exists. Alpha agonists have not been demonstrated to be helpful in
correcting male ISD. Periurethral collagen injections have been effective
in improving stress incontinence symptoms, but they rarely provide lasting
For women with intrinsic sphincter dysfunction, estrogen therapy and/or
alpha agonists have been used with some improvement in symptoms.
Periurethral collagen injections are most effective for women with ISD,
producing cure rates that last as long as 1 or 2 years. Although the
efficacy of periurethral injection therapy is better in women compared to
men, it does not produce lasting cure.
AMS 800 - The device
The most commonly used device today, the AMS 800 artificial urinary
sphincter is composed of a pressure-regulating balloon, an inflatable
cuff, and a control pump. The balloon has a dual function: it is a
pressure regulator as well as a fluid reservoir. Balloon reservoirs come
in 5 preset pressures (ie, 41-50, 51-60, 61-70, 71-80, and 81-90 cm
H2O). The lowest pressure required to close the urethra is
used. Balloon reservoirs typically are placed in the lower abdomen. For
uncomplicated bulbous urethral cuffs, the most commonly chosen reservoir
is the 61– to 70–cm H2O pressure balloon. For bladder neck
cuffs, the 71– to 80–cm H2O balloon reservoir is chosen.
The inflatable cuff has a variable length that compresses the urethra
or the bladder neck circumferentially. Cuff sizes range from 4.5-11 cm, in
0.5-cm increments. The cuff is placed around the bulbar urethra in adult
males. For women and children, the bladder neck is chosen. The cuff size
is based on the circumference of the bladder neck or the bulbar urethra. A
properly sized cuff for the bulbar urethra ranges 4.5-5.5 cm in length.
Most commonly, a 4.5-cm cuff is chosen for adult males. For the bladder
neck, a 6.0- to 8.0-cm cuff is selected in women.
The control pump contains unidirectional valves, a delayed-fill
resistor, a locking mechanism, and a deflate pump. The control pump is
small and easily concealed within a subcutaneous pouch in the scrotum or
the labia. The delayed-fill resistor is responsible for automatic cuff
repressurization. The cuff inflation takes 3-5 minutes, although bladder
emptying takes less time. A unique feature of this model is the locking
mechanism that can keep the cuff deflated for a prolonged period. The
locking mechanism is a small button located on the side of the control
Mechanics of the AMS 800
The artificial urinary sphincter works on the basis of hydraulic
mechanics. The isotonic fluid within the sphincter is transferred from the
reservoir to the cuff and vice versa in a unidirectional fashion. When the
sphincter is first activated (unlocked), the fluid from the reservoir
travels down the pressure gradient to the cuff. The cuff gradually
inflates to effectively close the urethra. This stores urine in the
bladder and prevents urine loss. The device works in semiautomatic
fashion, the cuff remaining closed at all times except when the patient
opens the cuff for voiding.
To void, the patient must open the artificial sphincter. The patient
manually squeezes the control pump that is located in the scrotum or the
labia. When the control pump is squeezed, the fluid in the control pump is
sent up to the balloon reservoir. It then automatically reexpands. As the
control pump reexpands, it pulls the fluid out from the cuff. This causes
the sphincter cuff to deflate. The patient repeats this maneuver (3-4
times) until the pump remains flat. This indicates that the cuff is
At this point, the urine flows freely from the bladder. Urination
commences until the bladder is empty. After 3-5 minutes, the fluid from
the balloon reservoir automatically flows through a delay-fill resistor
within the pump and down back to the cuff. When the cuff reinflates, the
urethra becomes effectively closed and the patient becomes dry. The
locking mechanism (button on the side of the control pump) allows the
physician to lock the cuff in an open or closed position. Typically, the
AMS 800 device is left locked (deactivated) in an open position at the
time of surgical implantation. After adequate healing has taken place, the
sphincter is unlocked (activated) by the physician. If the patient
inadvertently locks the button when the cuff is closed, urinary retention
occurs. Conversely, if the button is locked when the cuff is open,
persistent incontinence occurs.
Limitations of the AMS 800
The AMS 800 device is an extremely reliable prosthesis that is easy to
place. The patient satisfaction rate is high after successful
implantation. Despite recent advances in mechanical design, certain
limitations exist with this device. Mechanical malfunctions (ie, cuff
leak, defective pump) and surgical problems (ie, pump migration, improper
cuff size) require reoperation and sphincter revision. Urinary
incontinence may arise from improper usage, fluid leakage, pressure
atrophy, or cuff erosion. Urinary retention may occur as a result of
particle obstruction or a tube kink in the system.
- Silicone composition: The AMS 800 is composed of permeable silicone
elastomer. Although relatively inert and resistant to body fluids,
silicone deteriorates and loses tensile strength over time. Because it
is permeable, fluid escapes over time, with resultant decrease in
closing cuff pressure. The constant rubbing together of the 2 silicone
components can lead to thinning of the silicone elastomer and exacerbate
- The hydraulic system: The balloon, cuff, pump, and connecting
tubings are filled with iso-osmotic solution. Either isotonic sodium
chloride solution or radiocontrast is used. The tonicity of the contrast
is approximately 290-310 mOsm/L, similar to human intracellular and
extracellular fluid. The use of hypo-osmolar or hyperosmolar fluid
causes sphincter malfunction due to osmotic fluid shifts.
- Pressure-regulating balloon: The fluid volume of the
pressure-regulating balloon regulates the cuff pressure. A typical
balloon reservoir holds 20-22 mL of iso-osmotic fluid. The
pressure-volume relationship of the AMS 800 device is very narrow and
sigmoid curve shaped. Small volume changes (ie, 2 mL) decrease its
pressure characteristics; when the volume decreases below 14 mL, the
pressure decrease is precipitous. A common cause of postactivation
incontinence is fluid loss from the pressure-regulating balloon. The
patient notices that the number of squeezes to deactivate the pump has
decreased or the pump does not refill and remains flat. The incidence of
balloon leak responsible for sphincter malfunction has been reported to
be as high as 13% in some series.
- Inflatable cuff: A common problem leading to delayed or persistent
incontinence is fluid loss due to a wear defect in the cuff. The most
common site of fluid leak is the lower surface of the cuff. In 1983, the
inner surface of the cuff was reinforced with a layer of fluorosilicone
gel to prevent friction between 2 leaflets. With this modification, the
cuff leak rate decreased from 56% to 1.3%.
- Connecting tubing: A short tube length may disrupt connecting
junctions, causing a fluid leak or pulling up the control pump into the
inguinal area, making device manipulation difficult. Excess tube length
may lead to kinks, obstructing the system and causing urinary retention.
Kinks are rare after 3 months of device implantation. In the past, tube
kinks were the most common mechanical cause for surgical revision. With
the advent of reinforced kink-proof tubing, no mechanical failures have
been reported. However, tube kinks still may occur from tailoring
connecting tubes to an improper length during the implant procedure.
- Control pump: The control pump is cosmetically appealing due to its
small size. Yet, its small size can be a handicap because some patients
may have difficulty manipulating the pump. Labial or scrotal hematomas
may displace the pump into an unfamiliar location. The pump may rotate
upon itself and become kinked. Migration of the pump into the inguinal
region may cause failure to deflate the cuff.
- Locking mechanism: A major technologic advancement of the AS 800 is
its locking mechanism. The disadvantage is that activating and
deactivating the cuff using the locking mechanism is not always easy.
Before locking the cuff, one must be sure that some fluid remains in the
pump chamber. If the pump chamber is totally flat and empty, unlocking
(activating) the cuff in the standard fashion is impossible. If this
occurs, squeezing the sides of the locking button (located immediately
above the pump chamber) allows the fluid to return to the pump chamber
by circumventing the delay-fill resistor.
During the informed consent,
potential complications unique to this procedure should be discussed.
Potential complications include urethral injury, bladder injury,
mechanical failure, and persistent stress incontinence. The possibility of
surgical revision at a future date also should be discussed.
The operating room staff, as well as the surgeon, should be familiar
with the device, the equipment needed, and the surgical steps of the
procedure. It is helpful for the surgeon and/or the operating room staff
to observe the AMS 800 prosthesis implant procedure before surgery.
Prophylactic antibiotics should be administered, and the surgical team
should scrub for 10 minutes prior to commencing with the operation.
Once the patient is in the
operating room, the abdomen and genitalia are shaved. Following the shave,
the area is scrubbed with povidone-iodine soap for 10 minutes. For bulbous
urethra cuff placement, the patient is placed in the lithotomy position.
The patient is draped for both a perineal and an abdominal incision.
A plastic-draped Mayo stand is used as a station for handling and
filling of prosthetic components. The surgical setup should include a
broad-spectrum antibiotic solution for irrigation. The antibiotic solution
and the filling solution should be kept separate from each other.
Components should not have contact with paper or cloth drapes. Submerge
the filled components in a storage basin containing sterile sodium
chloride solution until they are ready for implantation.
Silicone components actively attract dust and lint. Glove powder that
enters the tubing may block the pump valves. Surgeons should wash their
gloves before making the tubing connections. The operative technique of
placing the urethral cuff is described below.
- Balloon reservoir placement: Make a suprapubic incision. A midline
or transverse incision is made. Divide the rectus fascia. Spread the
linea alba to reach the prevesical space. Use blunt dissection to create
a space for the balloon. Fill the balloon with 22 cc of the iso-osmotic
filling solution, aspirate the air, and evacuate the fluid from the
balloon. Clamp the tubing and position the balloon in the prevesical
space. Route the tubing through the rectus fascia to the abdominal
- Bulbous cuff placement
- Place a 14F Foley catheter. Make a midline perineal incision.
Identify the bulbocavernosus muscle. The bulbocavernosus muscle is
split in the midline and retracted laterally. Use a right angle clamp
to dissect around the bulbar urethra under direct vision. Dissect out
a 2-cm plane posteriorly around the urethra to accommodate the cuff.
Encircle a Penrose drain around the urethra and use it as a retractor
to facilitate urethral dissection. Exchange the Penrose drain for a
measuring tape. The urethral measuring tape is placed around the
urethra at the site where the cuff is to be implanted. The measuring
tape must fit snugly without constricting the urethra. Remove the
urethral catheter before measuring the urethra.
- Select the cuff size that corresponds to the measured length. The
cuff is prepared for implantation by injecting the filling solution
into the cuff, aspirating all of the air, and then evacuating the
fluid from the cuff. Place the cuff around the urethra. Pass the cuff,
tab first, under the urethra. Snap the cuff into place. Route the cuff
tubing suprapubically to the abdominal incision. Reapproximate the
bulbocavernosus muscle over the cuff followed by Colles fascia. Close
the perineal incision.
- Pressurizing the system
- To pressurize the cuff, the cuff tubing and the balloon tubing are
temporarily connected using a straight connector. Remove the catheter.
Flush the tubing ends to remove all debris. Fill the balloon with 22
cc of iso-osmotic filling solution. Temporarily connect the cuff
tubing and the balloon tubing using a straight connector. This allows
the cuff to pressurize. Wait 10-30 seconds. Clamp the cuff tubing and
the balloon tubing with silicone-shod hemostats and remove the
connector. Remove the hemostat and aspirate all of the remaining fluid
from the balloon. Refill it with 20 cc of filling solution. Clamp the
tubing with silicone-shod hemostat until the final connection is made.
This 2-step filling compensates for the potential pressure atrophy.
- In this author's opinion, pressurizing the cuff and the balloon
reservoir prior to making the final connection is optional and is not
truly necessary. This author does not perform this step but simply
fills the pressure reservoir with 23 mL of isotonic sodium chloride
solution (ie, 22 mL for the balloon and 1 mL for the cuff = total of
23 mL) and connects all the tubings after all components (ie, balloon,
cuff, pump) have been implanted. By not pressuring the cuff, the
operation is simplified without compromising the efficacy of the
- Pump implantation: To implant the control pump in the scrotum use
blunt dissection to create a dependent subdartos pouch. The control pump
should be placed on the same side where the pressure-regulating balloon
was placed. From the abdominal incision, dissect out the right
hemiscrotum for pump placement. After filling the pump with filling
solution, replace it in the scrotum. Place the pump in the most
dependent part of the scrotal pouch, making sure that it is palpable and
the locking button faces outward. The pump tubing should be above the
rectus muscle and fascia in the abdominal incision.
- Connections: After the components are placed, trim the excess
tubing. Connect the ends of the tubing using the sutureless Quick
connectors. Suture-tie connectors are used for revision surgeries.
Connecting tubings should lie above the rectus fascia.
- Checking the device: After the connections, the sphincter is cycled.
At the authors' institution, retrograde perfusion sphincterometry with
flexible cystoscopy is performed to check the integrity of the implanted
sphincter. After confirming the sphincter is working properly, the cuff
is locked in an open position (deactivated). To deactivate the device,
the pump is squeezed and released several times to empty the cuff. When
the cuff has refilled so that a slight dimple appears in it, the
deactivation button is pushed to lock the cuff open. During the healing
process, the cuff must remain locked in an open position. The abdominal
incision is closed. A small Foley catheter (ie, 14F) is placed.
Intravenous antibiotics are
continued until discharge. The Foley catheter is removed the day after the
surgery. The patients usually are discharged within 24-48 hours. At the
authors' institution, oral antibiotics are prescribed for 2 weeks after
Immediately after implantation, a 6- to 8-week deactivation period
allows healing. The cuff is left open in a locked state. Postoperatively,
the patient experiences preoperative stress incontinence until the
sphincter is activated. Thus, some protection must be used in the form of
pads, external condom drainage, or intermittent catheterization during the
Intermittent catheterization is not a contraindication to an artificial
urinary sphincter as long as the cuff remains deflated. Those with
bladder-neck cuff placement may perform self-catheterization without risk
to the cuff and the underlying tissue. However, patients with bulbous
urethral cuffs are at higher risk for injury from prolonged
Follow-up care: The patient is instructed not to
manipulate the sphincter for 6 weeks. The first postoperative clinic visit
is in 1-2 weeks, at which time the abdominal and perineal incisions are
inspected for skin integrity and wound infection. At 6-week follow-up, the
sphincter is activated by applying a firm, forceful squeeze to the control
pump. The patient is instructed on the proper use of this device by the
physician and videotape.
All patients require direct visual demonstration of sphincter use after
activation. Some patients are more adept than others in learning how to
operate the pump. Improper cuff use is the most common cause of
postactivation urinary incontinence. Patients experience incomplete
emptying and overflow incontinence if the cuff is not opened properly.
Lack of education or difficulty manipulating the pump leads to inadequate
cuff deflation and sphincter malfunction.
If these patients are treated in the emergency department or if they
require hospitalization for a medical problem, they are instructed to
inform their treating physician that they have an artificial urinary
sphincter. Passage of a catheter or any other instrument through the
urethra without deflating the cuff and deactivating the device first may
result in sphincter injury.
For excellent patient education resources, visit eMedicine's Procedures
Center. Also, see eMedicine's patient education article Cystoscopy.
The AMS 800 device
See Limitations of the AMS 800 under Treatment for a discussion of
- Infection: Because artificial urinary sphincter is a synthetic
device, it is at risk of bacterial infection. The most common infecting
organism is Staphylococcus epidermidis. Other pathogens include
Proteus species, Pseudomonas species, Escherichia
coli, Serratia species, Corynebacterium, and
Enterobacter species. Meticulous aseptic techniques must be
exercised during sphincter implantation. Perioperative antibiotics with
gram-positive bacteria coverage are imperative. Traffic in the operating
room must be minimized. After surgical implantation, prophylactic
antibiotic coverage is recommended for patients undergoing any dental
- Pressure-regulating balloon: The balloon reservoir is placed
intra-abdominally or in an extraperitoneal prevesical space (space of
Retzius). For patients with prior pelvic surgery, scars and adhesions
increase the risk of bladder perforation. Iatrogenic peritoneotomy and
bowel injury has been reported. If bowel injury occurs, the implantation
must be abandoned.
- Inflation cuff
- Urethral injuries result from direct perforation or tissue
necrosis due to thermal injury. Most urethral injuries occur at the 12
o'clock position, where the urethra is adherent to the corpus
cavernosa. This is the most difficult site of dissection. Unrecognized
urethral injuries result in early cuff erosion and incontinence.
Bulbar placement in a prepubescent male should not be performed
because the tissues are thin and the risk of erosion is high. Cuff
implantation at the bladder neck is more difficult than at the bulbar
- In females, a correct plane between the bladder neck and vagina
must be identified to avoid injury to the urethra, vagina, and rectum.
To aid in the cuff placement, the use of Cutter clamp and cystoscopy
have been employed. Some surgeons open the bladder prior to dissection
in order to visualize ureteral orifices and the bladder neck. Vaginal
injuries are closed primarily. If a rectal injury occurs, the
procedure must be abandoned.
- Connecting tubing: The presence of particulate matters in the tubing
increases the risk of sphincter malfunction. A few air bubbles entering
the system are harmless because they are absorbed. However, aggregation
of air bubbles into an air lock can obstruct the pump. Blood clots also
can obstruct the connecting tube or the valves in the pump. Therefore,
care is taken to prevent entry of particulate matter into the system by
flushing the air bubble/blood clot out of tubing during surgery.
- Tissue atrophy
- A common cause of recurrent stress incontinence is loss of cuff
compression due to tissue atrophy. Tissue atrophy has been reported as
the most common cause of surgical revision, occurring in as may as
33-39% of cases in the literature (Gundian, 1989; Goldwasser, 1987).
Martins and Boyd (1995) reported that inadequate cuff compression
after presumed urethral atrophy accounted for 74% (ie, 60 out of 81
cases) of the recurrent stress incontinence in artificial urinary
sphincters placed after a major pelvic surgery and/or radiation.
- Tissue atrophy results from local tissue ischemia around the cuff.
Tissue atrophy, in turn, causes poor mucosal coaptation and incomplete
urethral occlusion. When the cuff inflates and deflates normally yet
the patient remains incontinent, tissue atrophy should be suspected.
The patient may notice the need to squeeze the pump more often to
deflate the cuff. Usually, symptoms of tissue atrophy manifest
approximately 4 months after initial device activation.
- In 1987, a new narrow backed cuff was introduced to decrease the
incidence of tissue atrophy. By decreasing the width of the outer
leaflet from 2 to 1.5 cm while maintaining the inner leaflet dimension
of at 2 cm, cuff pressure transmission to the urethra was improved.
This modification allowed the inner cuff leaflet to compress a wider
surface area without increasing the occlusive pressure. This new
innovative design has decreased the reoperation rate to 0-9%.
- Another method of retarding tissue atrophy is nocturnal
deactivation of the cuff. The cuff is locked in an open position
during the night when the patient is asleep. Nocturnal deactivation of
the device has been reported to reduce tissue atrophy by decreasing
the potential ischemia time.
- If tissue atrophy occurs, balloon pressure can be increased to the
next higher pressure (ie, from 61-70 to 71-80 cm H2O) to
increase the urethral closing pressure. If this fails, the cuff can be
downsized to a next smaller size or double cuffs may be placed.
Alternatively, the cuff site may be changed to a different area with
better tissue integrity.
- Cuff erosion
- The most feared complication of artificial urinary sphincter is
cuff erosion. Cuff erosion most commonly occurs within 3-4 months
after surgery. Early cuff erosion suggests unrecognized injury to the
bladder neck or urethra at the time of surgery. Erosion also may occur
as a result of periprosthetic infection or pressure necrosis. The site
of erosion can be localized by urethroscopy; cuff protrusion through
the urethral mucosa is unmistakably visible. The incidence of cuff
erosion has been reported to be 0-19%. The most significant risk
factor for delayed cuff erosion is pelvic radiation. The incidence of
erosion is 10-20% in irradiated patients.
- Efforts to minimize the incidence of cuff erosion include delayed
activation, nocturnal deactivation, and use of a low-pressure
reservoir. Delayed cuff activation has led to a 6% erosion rate with
AMS 800 models. Nocturnal deactivation has been felt to reduce the
risk of erosion. Using a balloon with a pressure less than 71-80 cm
H2O also decreases the risk.
- Early signs of erosion include gross hematuria, burning perineal
pain, and swelling at the cuff site. If the erosion is clean and
uncomplicated, only the cuff may be removed. A new cuff may be placed
3-6 months later. If purulent drainage is obvious, removal of all
sphincter units is mandatory.
- Women of childbearing age should be warned of the danger of cuff
erosion during abdominal delivery. As the baby crowns through the
vaginal introitus, the baby's head may compress the cuff against the
pubic symphysis, risking cuff erosion. Elective cesarean delivery or
deactivation of the artificial urinary sphincter in the final
trimester is recommended to minimize the risk of cuff erosion in this
Troubleshooting the AMS 800
- Radiographic studies
- Radiologic evaluation is an important means of troubleshooting a
malfunctioning sphincter if contrast is used as a filling medium.
Radiograph of the lower abdomen is the single most important test to
obtain if contrast is present. If isotonic sodium chloride solution is
used as fluid medium, radiographic evaluation does not help because
silicone components are not radio-opaque.
- Inflate-deflate radiographs are needed to assess the function of
the sphincter. When the cuff is open, the pump and the balloon
reservoir should contain some contrast, and the cuff should have none.
When the cuff is closed, a doughnutlike circumferential ring of
contrast should be visible at the cuff site. If the radiographic
contrast is absent, leak has occurred.
- Urethral pressure profilometry: Urethral pressure profilometry is a
nonradiologic test of sphincter function. Withdrawal urethral pressure
profilometry should be conducted with the cuff in both inflated and
deflated modes. Minimal pressure differential between 2 modes suggests
- Perfusion sphincterometry: Retrograde perfusion sphincterometry with
cystoscopy is a useful test to assess the integrity of the sphincter
unit. If time to inflate the cuff is longer than usual or the urethra
remains open, either cuff malfunction or tissue atrophy has occurred. At
the authors' institution, retrograde perfusion sphincterometry with a
flexible cystoscope is performed routinely at the time of sphincter
- Electrical conductance testing: Reoperation often is required to
service the malfunctioning device. At the time of operation, the use of
electrical conductance testing (ohmmeter) aids in identifying the faulty
component and the site of leak. Leaks at connector sites and the balloon
stem are excluded first. If the ohmmeter cannot be used to identify the
leak site, the pressure in the balloon reservoir can be measured by
connecting the tubing to a pressure transducer or by aspirating and
measuring the volume in the balloon.
American Medical Systems (AMS,
the manufacturer of the artificial urinary sphincter) has placed over
15,000 artificial urinary sphincters in men and women. The AMS 800 allows
over 80% of patients to be completely continent and over 90% to be
socially dry. The current rate of revisions varies from 0.3-0.6%. Patients
who benefit most are those who can empty their urinary bladder and do not
need intermittent catheterization.
Placement of an artificial
urinary sphincter (AMS 800) is an excellent surgical treatment for men,
women, and children with type III stress urinary incontinence. Extremely
reliable and durable, it has greatly improved quality of life for those
patients plagued by SUI. For men who are incontinent postprostatectomy,
the AMS 800 device is the only therapy that provides a consistently
lasting cure for stress incontinence.
Despite recent advances in mechanical design, certain limitations exist
with this device. When mechanical malfunctions and surgical problems
arise, repeat surgery often is diagnostic and therapeutic. With continued
advances in biomechanical engineering, an even better artificial urinary
sphincter that approaches the function of a biological urinary sphincter
should be forthcoming.
Insertion of an artificial urinary sphincter in a female patient is
controversial. The long-term success rates of female artificial urinary
sphincter placement have been reported to be 86-88% in the European
literature (Heitz, 1997; Marques, 1999). However, implantation of the AMS
800 device in a female patient is fraught with potential complications
that include vaginal, bladder, and urethral perforations. Additional
complications include urethral erosion or wound infection necessitating
device removal. Due to alternative effective surgical options such as
pubovaginal sling or periurethral injection therapy, implantation of
artificial urinary sphincter in an incontinent female is rarely performed
in the United States.
The presence of recurrent vesical neck contracture in combination with
postprostatectomy stress incontinence is a difficult problem to treat.
Recurrent bladder neck contractures often are treated with incision
(direct vision internal urethrotomy [DVIU]) or transurethral incision
(TUIVNC) followed by implantation of an artificial urinary sphincter.
Alternatively, intermittent catheterization is advocated to allow the
contracture to "soften-up" and stabilize over time. After the contracture
has stabilized, an artificial urinary sphincter may be placed. The exact
timing of sphincter placement is tailored to each individual. Recently,
Elliott et al (2001) have reported their positive experience with staged
artificial urinary sphincter placement after incision of vesical neck
contracture followed by UroLume stent.
|Caption: Picture 1. Artificial
urinary sphincter (AMS 800) is composed of pressure-balloon
reservoir, inflate-deflate cuff, and miniature control pump.|
|Caption: Picture 2. Artificial
urinary sphincter. Patient is placed in dorsolithotomy position.
Perineal incision has been made below the scrotum. Colles fascia is
being dissected off.|
|Caption: Picture 3. Artificial
urinary sphincter. Bulbocavernosus muscle has been dissected off.
The bulbar urethra is exposed.|
|Caption: Picture 4. Artificial
urinary sphincter. The right angle is passed behind the bulbar
|Caption: Picture 5. Artificial
urinary sphincter. The measuring tape is passed around the bulbar
urethra. The bulbar urethra measures 4.5 cm; thus, a 4.5-cm cuff is
chosen for implantation. |
|Caption: Picture 6. The
artificial urinary sphincter cuff is passed, the tab end first,
around the urethra. The cuff is snapped into place.|
|Caption: Picture 7. The tab of
the artificial urinary sphincter cuff is rotated dorsally. |
|Caption: Picture 8. Artificial
urinary sphincter. The cuff is seated in an excellent position. The
tubing from the cuff is passed up to the suprapubic wound where it
is connected to the control pump. |
|Caption: Picture 9. Artificial
urinary sphincter. The perineal incision is being closed. The Colles
fascia is closed. The skin is closed next.|
|Caption: Picture 10. Artificial
urinary sphincter. The balloon reservoir has been placed into the
subrectus space, and the control pump has been inserted into the
right hemiscrotum. The connecting tubes, meaning the cuff, pump, and
reservoir, are all connected.|
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