Open Journal of Urology, 2011, 1, 91-93
doi:10.4236/oju.2011.14020 Published Online November 2011 (http://www.SciRP.org/journal/oju)
Copyright © 2011 SciRes. OJU
Beware of the Dog: Traumatic Extrusion of an Artificial
Urinary Sphincter Following Blunt Trauma to
the Scrotum by a Domestic Animal
Michael S. Floyd Jr.*, Karen Chan, Andrew D. Baird
Department of Urology, Aintree University Hospital, Liverpool, Uni t e d K i ng dom
Received September 14, 2011; revised October 28, 2011; accepted November 10, 2011
Artificial urinary sphincters are commonly used in males with intrinsic sphincter deficiency to improve con-
tinence and quality of life. Complications include erosion, mechanical failure and infection. Frequently, a
staged approach involving removal of the device, followed by a period of healing and subsequent reinsertion
of a new sphincter is required to restore continence. We describe the first case ever reported of traumatic
sphincter extrusion following blunt scrotal trauma by a dog and review its clinical features and management.
Keywords: Sphincter, Erosion, Trauma, Artificial, Urinary
1. Case Report
A 59 year old man presented to out patients with a three
month history of a discharging wound in his perineum
adjacent to the bulbar urethra. He also complained of
urinary loss through this sinus when voiding. There was
a recent history of trauma having sustained a headbutt to
the scrotum by a dog. His past history was remarkable
for an industrial accident in 1981 in which he sustained a
pelvic fracture and vesicourethral distraction defect. This
had been initially managed with a urethroplasty to re-
store his urethral integrity and the subsequent insertion
of an Artificial Urinary Sphincter (AUS) for continence
purposes. This was removed soon after insertion as it had
become infected. Eight years later a second successful
attempt was carried out to insert a second artificial uri-
nary sphincter and this lasted a further ten years until
mechanical failure occurred. This was again revised but
on activation of this third sphincter continence was not
successfully achieved. Finally, a fourth urinary sphincter
was successfully implanted with restoration of conti-
nence in 1999. Th is had successfully worked up until th e
recent trauma which occurred when a dog head butted
the patient in the scrotum and perineum. Immediately
following the event he developed pain and swelling which
subsided. Several months after the event he developed a
sinus on the left side of his perineum through which
urine dripped following deflation of the sphincter cuff to
allow satisfactory uret hr al v o iding.
Initial surgical management involved examination
under anaesthesia, cystoscopic evaluation and removal of
the eroded, infected sphincter. Physical examination re-
vealed a cutaneous fistula at the left side of his perineum
near the scrotal junction. (Figure 1) Rigid cystoscopy
revealed a urethral erosion at the junction of the mid and
distal bulbar urethra with the sphincter cuff visible on the
left side of the urethral defect. A 14 french silicone
catheter was inserted with the assistance of a guidewire
to allow urethral healing. Using a perineal incision the
Figure 1.Cutaneous fistula at the junction of the left hemis-
crotum and perineum with visible sphincter erosion.
M. S. FLOYD JR ET AL.
bulbar urethra was exposed allowing visualisation of the
urethral erosion and the cuff was explanted from around
the urethra. (Figure 2) Monofilament absorbable sutures
were used to restore urethral integrity. A separate inci-
sion over the right inguinal area allowed for successful
extraction of the pump and its tubing. Finally, a right
iliac fossa scar permitted delivery of the reservoir and its
tubing as well as allowing the old scar to be excised.
(Figure 3) The catheter was left in situ for three months
Figure 2. A perineal incision was used to remove the sphi-
ncteric cuff and visualize the urethral erosion.
Figure 3. A right iliac fossa scar was used to remove the
sphincter reservoir. The scrotum is deflected toward the
right showing the perineal incision and the old inguinal scar
that was excised.
to allow wound healing. A Magnetic Resonance image
(MRI) of pelvis was carried out at six weeks which re-
vealed no pelvic collections or abscess formation. The
second stage of his management involved the reinsertion
of a fifth artificial sphincter six months after removal
followed by sphincter activation six weeks later.
Surgical management of urinary incontinence was revo-
lutionised following th e invention of the artificial u rinary
sphincter by Foley in 194 7 and the subsequent implanta-
tion by Scott in 1972 [1,2]. Less invasive treatments have
been developed over time such as collagen injections and
the male urethral sling but the artificial urinary sphincter
remains the gold standard for male incontinence.  In
male patients, the bladder neck is the usual insertion site
unless precluded by a history of disease or trauma. In
specific cases of post prostatectomy incontinence the
bulbar urethra can be used but with higher complication
rates.  In females the bladde r neck is the only insertion
site. The artificial sphincter mechanism consists of three
basic components which work hydraulically : 1) an
inflatable cuff placed around the bladder neck, 2) a pres-
sure regulating balloon or reservoir fitted extraperito-
neally and 3) a pump which is placed immediately be-
neath the scrotal skin in a dartos pouch in males or labia
majora in females.  The pump mechanism further in-
corporates a valve, a refill delay resistor and a deactiva-
tion button. The three main components are connected by
fluid filled tubes and are activated by squeezing on the
pump allowing fluid transfer from the reservoir to the
inflatable cuff.  Pressure within this clo sed system and
by inference, the occlusive pressure of the cuff (available
in different sizes) is dependen t on the pressure regulating
balloon and is decided intraoperatively by the surgeon
There is limited long term data on artificial urinary
sphincter outcome . Initial reports revealed high com-
plication and revision rates but with acceptable outcomes.
Duncan et al.  have reported a series of late complica-
tions with the longest interval recorded between implan-
tation and erosion being seven years. Venn et al.  in
2000 reported that 37% of devices implanted were re-
moved during a ten year period due to either infection or
erosion and highlighted that the risk of cuff revision is
higher if placed around the bulbar urethra as opposed to
the bladder neck. Kim et al.  reported an overall com-
plication rate of 37% with mechanical failure, erosion
and infection being the three most common complica-
tions . No specific differences were found between
complications and artificial sphincter characteristics.
Over two years prior sphincter revision surgery itself is a
Copyright © 2011 SciRes. OJU
M. S. FLOYD JR ET AL.
Copyright © 2011 SciRes. OJU
risk factor for sphincteric erosions and continence rates
are lower in patients presenting for revision surgery for
erosions compared to other causes such as previous ra-
diation therapy. Lai et al.  followed four specific
patient groups who underwent artificial sphincter inser-
tion and found the rate of cuff erosion to be 6% occur-
ring at a mean of 19.8 months . However, the four
groups (rad iated, non rad iated, neurogen ic and second ary)
displayed no difference in the rate of complications or
the need for device explant. However, the risk of atrophy,
mechanical failure and the need for revision (compared
to the risks of infection and erosion) did increase as the
study progressed with sphincter cuff atrophy being the
Two complication types require a surgical approach.
Complications such as infections and urethrocutaneous
erosions require device removal. Separately, complica-
tions such as disconnection or leakage causing fluid ex-
travasation with a resultant pressure fluctuation within
the artificial sphincter frequently require repair, but not
necessary removal .
There are reports of unusual presentations of urethral
erosions in patients on steroid therapy who have under-
gone repeated urethral catheterisations without cuff de-
flation in the intensive care setting and who have subse-
quently presented with delayed erosions and worsening
incontinence . Previous authors have alluded to the
role of trauma as a potential aetiological factor in artifi-
cial sphincter erosion but do not mention the mechanism.
 Similar to this case all patients were initially man-
aged by removing the infected device.
In this case we report a case of erosion of a urinary
sphincter following blunt trau ma to the scrotum by a dog
necessitating removal of the device and reinsertion of a
fifth sphincter six months later. We believe this to be the
only recorded case of sphincter extrusion caused by blunt
trauma from a domestic animal. Similar to other cases of
delayed erosion due to infection our patient was man-
aged with a staged approach, involving explant of the
damaged sphincter and reinsertion of a new sphincter
after a period of wound healing. Given the previous his-
tory of AUS insertion in our patient and visible cutane-
ous erosion, repair of the affected components was not a
viable surgical option.
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