Reprinted from December 2010
the Science Behind Positive Patient Outcomes
RP1556
Supported and approved by
the Science Behind
Positive Patient Outcomes
Advances in Anal Fistula Repair:
Minimizing Risk for Incontinence
An Interview With:
Michael J. Stamos, MD
Professor of Surgery
Chief, Division of Colon and Rectal Surgery
University of California at Irvine
School of Medicine
Irvine, California
influence outcomes in single-center studies, including patient selection, peri-procedural management, and operator experience, the relative efficacy of these methods remains uncertain. In this summary,
2 surgeons describe a rational approach to patient selection for anal
fistula plugs. Each surgeon details the advantages and limitations of
a conservative approach. They both selectively employ anal fistula
plugs as an alternative to fistulotomy with slightly different criteria.
Background
Elizabeth McConnell, MD
Clinical Research Faculty
Arizona State University
Clinical Teaching Professor
St. Joseph’s Hospital
Owner, McConnell Colorectal Center and
Arizona Outpatient Surgery
Phoenix, Arizona
Introduction
Fistulotomy, although effective for repair
of intersphincteric and low transsphincteric
anal fistulae, poses a substantial risk for complications, particularly incontinence, in the
treatment of high transsphincteric fistulae.
Additionally, complex fistulae are not amenable to fistulotomy, and they include fistulae
involving greater than 30% of the external
sphincter, anterior fistulae in females, multitract fistulae, horseshoe fistulae, and patients
who have pre-existing incontinence, local
irradiation, or Crohn’s disease. In such fistulae, 2 commercially produced biodegradable
plugs are among the options for conservative repair. The efficacy of conservative
options, which also include placement of
setons, use of fibrin glue, construction of an
endorectal advancement flap, and the ligation of the intersphincteric fistula tract (LIFT)
procedure, largely has been defined by case
series, often at single centers. Due to the
limited controlled studies and variables that
1 General
SurgeryPublishing
NEws December 2010
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© 2012 McMahon
Reliable data on the precise incidence of anal fistula in the United
States are not available, but surgical centers recognize this condition
as a common source of referral. In an epidemiologic study undertaken in Finland, the incidence over a 10-year period approached
10 per 100,000 with a concentration among adults in their 30s and
40s.1 Although anal fistulae can occur at any age, the mean age in
the European study was 38.8 years. The incidence was about twice
as common in men as in women (12.3 vs 5.6 per 100,000 cases).1
The pathophysiology of anal fistula and the reason for a peak
incidence in young to middle-aged adults remains controversial, but infection in cryptoglandular
spaces of the anal canal is a frequently
cited hypothesis for the initiating event.2
The theory is that an abscess formed by
infection in glands surrounding the anal
canal progresses into formation of the
fistulae that connect the muscular wall
of the sphincter to the perianal skin.
Although it is believed that all fistulae
originate as abscesses, only a proportion
of abscesses progress to fistulae.3
In the Parks Classification system,
anal fistulae, defined by their position in
relationto the anal sphincter, are described
as transsphincteric, intersphincteric,
suprasphincteric,or extrasphincteric.4 The
most common presentation is intersphincFigure 1. The design of the GORE®
teric,
followed by transsphincteric. The
BIO-A® Fistula Plug features bundled
remaining 2 types are relatively uncomhollow tubes attached to a circular disk.
mon. The position of the anal fistulahas
The disk helps the plug stay in place,
critical importance to the choice of therreducing the chance for extrusion of
apy. High transsphincteric fistulae, which
the plug. It also facilitates reproducible
are defined by involvement of at least
anchoring for dependable performance.
one-third of the external anal sphincter
the Science Behind Positive Patient Outcomes
muscle as assessed by clinical examination or radiological imaging, are regarded as the most challenging.5
While fistulotomy is effective in 80% to 90% of primary fistulae, it poses a risk for complications and does not preclude recurrences.6 For high transsphincteric or other complex fistulae, the
risk that incontinence will followfistulotomy is so great that most
surgeons consider the procedure inappropriate.7 The range of
reported continence disturbance after fistulotomy ranges from
0 to 64%.7-9 A cutting seton may also be used to perform a staged
fistulotomy; however, incontinence resulting from this approach
can be significant (2% to 63%).10
Alternative treatments have been pursued in high transsphincteric fistulae or complex fistulae, such as those with multiple
channels. In patients with high transsphincteric or complex fistulae, fistulotomy is less attractive because of a need for significant injury of the sphincter muscle that can lead to incontinence,
making more conservative measures a reasonable choice for preserving options.3 Although success rates may be no greater with
conservative measures, there are numerous advantages when
healing is achieved, including less risk for morbidity, the potential
for lower cost, and faster recovery.
The disadvantages of several conservative therapies include a
high rate of failure. Some techniques, such as fibrin glue, that have
produced fistula closure rates of less than 20% in some series
are no longer widely used.11,12 Success with endorectal advancement flaps has been variable: A review of the literature from 1978
to 2008 shows efficacy rates from 36.6% to 98.5%, with reported
incontinence ranging from 0 to 35%.13 The LIFT procedure is promising but relatively new and has not been well studied outside of
centers that pioneered the technique.14-16 As a result, the efficacy in transsphincteric and complex fistulae, compared with other
conservative techniques or fistulotomy, remains poorly defined.
Anal fistula plugs also have been associated with variable success rates, but there are differences between the 2 available
devices. The first commercially available anal plug in the United
States was developed from lyophilized porcine intestinal submucosa (COOK® BIODESIGN™ SURGISIS® Fistula Plug, Cook Medical
Inc., Bloomington, IN), which was created into a conical shape
for insertion to the fistula tract. Although this plug, which was
licensed by the FDA in 2005, was superior to fibrin glue for closure
of high transsphincteric fistulae in a 25-patient, nonrandomized
study,17 the limitations of fibrin glue made this efficacy difficult to
interpret. Subsequent studies suggested that this device yields
relatively low success rates in the complex and challenging fistulae for which it is most needed, falling as low as 13.9% in some
series.18,19
The newer of the 2 anal fistula plugs, licensed by the FDA in
2009 (GORE® BIO-A® Fistula Plug, W. L. Gore & Associates, Inc.,
Flagstaff, AZ), is a 100% bioabsorbable, synthetic construction
(polyglycolic acid:trimethylene carbonate) that employs a tubelike structure intended to provide a greater barrier to dislodgement (Figure 1). The scaffolding of the synthetic material allows
cells to migrate into the matrix and tissue formation begins as the
body gradually absorbs the material. As it is absorbed, the material is replaced with native tissue,20 predominantly type 1 collagen,
in an approximately 1:1 ratio over time (Figure 2).21 In addition, the
plug is engineered to conform to the tract and reduce the likelihood of plug dislodgement. Initial healing rates reported by 2
experts experienced with this device have been encouraging and
suggest this is a useful tool when used selectively.
Michael J. Stamos, MD: Current Application of
Anal Fistula Plugs
In the treatment of complex anal fistulae, therapy must always
be individualized. Although the success rate with fistulotomy in
uncomplicated fistulae may exceed 95%,6 neither surgery nor conservative measures achieve this type of success in fistulae that are
complex (as defined by a high transsphincteric
location, prior treatment failure, or the presence of multiple tracts). Once complex fistulae
are drained—typically with seton placement—
and infection has been controlled, it is reasonable to provide patients with treatment options
that may include advancement flap surgery,
anal plug placement or, in some cases, the LIFT
procedure (Figure 3).
The advantage of the anal fistula plug is that
it preserves all other treatment options. In particular, flap surgery remains viable in the event
success is not achieved. Although flap surgery has the potential for definitive repair, the
risk for incontinence is substantial in difficult
a) Human explant at 3 months (Milligan’s
b) Human explant at 13.5 months
cases. This encourages many patients to select
trichrome, 10× magnification).21
(Milligan’s trichrome, 4× magnification).21
a fistula plug, which has become an attractive
option since the Gore device was introduced,
Figure 2. Bioabsorbable material degradation is visible as collagen (green) fills
as an initial procedure. The previous plug, the
the space.
COOK® BIODESIGN™ SURGISIS® Fistula Plug,
2 General Surgery NEws December 2010
Supported and approved by
Complex Anal Fistula
Draining Station
Anal Fistula Plug
If fails
If fails
Repeat Plug
LIFT
If fails
If fails
Figure 3. Algorithm for complex anal fistula treatment.
LIFT, ligation of the intersphincteric fistula tract
Image courtesy of Michael J. Stamos, MD.
Advancement
Flap
transsphincteric fistulae, the plug appears to
pose a minimal risk for incontinence versus other
conservative procedures, such as the endorectal
advancement flap. Moreover, hospital length of
stay (outpatient procedure) and recovery time
are shorter relative to flap surgery. The synthetic
plug is easily secured in place by suturing the
disk into the anorectal mucosa and muscularis
(Figure 4). Although Dr. Stamos does not employ
a pocket flap to further reduce the risk for plug
dislodgement, he noted that this might be useful in some cases.
Patient selection and education are critical. Although the newer plug can be employed
effectively to reduce the need for more invasive surgery and the risk for incontinence in
many complex fistulae, surgeons need to prepare patients for potential unresolved fistula,
as is known to occur with complex anal fistulae. When effective, the anal fistula plug is a
relatively simple procedure with few technical
demands that also preserves alternative treatment options. “In my experience success rates
have been approximately 50%,23 which compares favorably to alternatives even though it
is among the least invasive approaches,” said
Dr. Stamos.
Elizabeth McConnell, MD: Current
Application of Anal Fistula Plugs
For complex fistulae, the anal fistula plug can
be an effective treatment once the fistula has
matured, usually following a period in which a
drainage
seton has permitted the fistula to stab) The GORE® BIO-A® Fistula Plug can be
a) The device is pulled into the tract until
bilize. At this point, it becomes clearer which
securely seated at the internal opening
the disk lies flat and is well apposed to the
approach might be most suitable. In cases when
by covering it or by suturing the disk to
anorectal mucosa.
minimal division of the sphincter is involved, fisthe anorectal mucosa and muscularis, as
tulotomy is effective with an acceptable risk for
shown in this case.
incontinence. In patients with a complex fistula for whom a conservative approach may be
Figure 4. Securing the GORE® BIO-A® Fistula plug in the anorectal mucosa and
more attractive to circumvent the risks associmuscularis.
ated with surgery, the fistula plug often is an
attractive choice.
was not effective in well-designed studies. In a prospective study
Due to a low rate of success, mainly resulting from dislodgement,
of consecutive patients published 2 years after the plug was made Dr. McConnell discontinued use of COOK® BIODESIGN™ SURGISIS®
available, the success rate was only 41%.22 “Dislodgement has Fistula Plug after an initial patient series. However,based on changes
been a particularly common problem, and my success rates were in design and reports of improved outcomes with the GORE ®
sufficientlydisappointing that I abandoned this procedure,” said BIO-A® Fistula Plug, she reintroduced this device into her treatment modality approximately 18 months ago. Since that time, Dr.
Dr. Stamos.
The design features of the GORE® BIO-A® Fistula Plug, particu- McConnellhas treated a total of 20 fistulae in 12 patients, with
larly a structure that permits a tighter fit into the fistula, has revived a fistula placement success rate of 75% (15 of 20 fistulae) and a
the viability of this option, which Dr. Stamos has been employ- patient success rate of 67% (8 of 12 patients) for patients followed
ing routinely since these became commercially available. In high at least 12 months. These rates are equivalent to her experience
General Surgery News December 2010 3
the Science Behind Positive Patient Outcomes
with the LIFT procedure, but the fistula plug better preserves
options in the event of failure. In many cases, it is appropriate to
make a second attempt with the fistula plug. Although success on
second attempts has been lower, at approximately 50% (2 successful fistulae in 4 repeat attempts), this rate of success remains
substantial for a relatively noninvasive approach to a challenging problem.
“In my experience with the fistula plug by Gore, patients often
are uncomfortable during the initial 3 days after the procedure,
which may be the result of an inflammatory reaction, but patients
warned of this phenomenon usually are tolerant, and the pain typically resolves completely after this period,” said Dr. McConnell.
In successful treatment, healing may be achieved within 60 days,
although longer healing may be required and failure should not be
declared until at least 4 months of follow-up. Dietary counseling,
particularly an emphasis on high-fiber diets, is an essential part of
efforts to increase healing and prevent recurrence.
Not all patients with complex fistulae are candidates for anal fistula plugs even if they are not well suited for surgery. Dr. McConnell
does not employ anal fistula plugs in women with anterior fistulae
or in patients with diabetes with posterior fistulae, but her experience has provided much confidence for the use of the GORE®
BIO‑A® Fistula Plug in routine care when employed selectively.
“When these are effective, they allow patients to undergo a relatively simpleprocedure with a very low risk for complications
and without eliminating other treatment options if success is not
achieved,” said Dr. McConnell.
Conclusion
Complex anal fistulae pose a significant clinical challenge because
not all of the variables that influence treatment success are fully
understood. Although surgery may offer one of the most reliable
approaches for the goal of fistula closure and healing, the associated risk for incontinence makes more conservative approaches
preferable in complex cases. Of conservative options, the newer
anal fistula plug is a relatively simple device, with an encouraging
rate of healing relative to other conservative options.
References
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1337-1342.
11. Buchanan GN, Bartram CI, Phillips RK, et al. Efficacyof fibrin sealant in the management of complex anal fistula: a prospective trial. Dis Colon Rectum. 2003;46(9):
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12. Sentovich SM. Fibrin glue for anal fistulas: long-term results. Dis Colon Rectum.
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21. W. L. Gore & Associates, Inc. 2006. Doerhoff, CR. Immunohistochemical Assessment of Collagen in an Explanted GORE Bioabsorbable Hernia Plug at 13.5 months.
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DISCLAIMER:
This article is designed to be a summary of information. While it is detailed, it is not
an exhaustive clinical review. McMahon Publishing, W. L. Gore & Associates, Inc., and
the authors neither affirm nor deny the accuracy of the information contained herein.
No liability will be assumed for the use of the article, and the absence of typographical
errors is not guaranteed. Readers are strongly urged to consult any relevant primary
literature. Copyright © 2012, McMahon Publishing, 545 West 45th Street, New York,
NY 10036. Printed in the USA. All rights reserved, including the right of reproduction,
in whole or in part, in any form.
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463-469.
3. Hamalainen KP, Sainio AP. Incidence of fistulas after drainage of acute anorectal
abscesses. Dis Colon Rectum. 1998;41(11):1357-1361; discussion 61-62.
4. Parks AG, Gordon PH, Hardcastle JD. A classification of fistula-in-ano. Br J Surg.
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5. Wang JY, Garcia-Aguilar J, Sternberg JA, Abel ME, Varma MG. Treatment of transsphincteric anal fistulas: are fistula plugs an acceptable alternative? Dis Colon
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after anal surgery. Dis Colon Rectum. 2004;47(10):1643-1649.
4 General Surgery NEws December 2010
Gore products referenced within, if any, are used within their FDA approved/cleared
indications. Gore does not have knowledge of the indications and FDA approval/
clearance status of non-Gore products. Gore makes no representations as to the
surgical techniques, medical conditions or other factors that may be described in this
article. The reader is advised to contact the manufacturer for current and accurate
information. AQ0106-EN1
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8. Omner A, Wenger FA, Rolfs T, Walz MK. Continence disorders after anal surgery—
a relevantproblem? Int J Colorectal Dis. 2008:23(11):1023‑1031.