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21 Fistula-in-Ano
335
Fig. 21.2 Goodsall’s rule (With permission from Vasilevsky [ 2 ] )
extension [ 3 ]. Digital rectal examination may reveal an
indurated cord-like structure beneath the skin in the direction of the internal opening with asymmetry between right
and left sides. Internal openings may be felt as indurated
nodules or pits leading to an indurated tract [ 3 ]. Look for
posterior or lateral induration that may be palpable, as this
may indicate fi stulas deep in the postanal space or horseshoe fi stulas [ 3 , 4 ]. Bidigital rectal examination will defi ne
the relationship of the tract to the sphincter muscles and
provides information as to preoperative sphincter tone,
bulk, and voluntary squeeze pressure that need to be
assessed.
Anoscopy is done prior to operation in an attempt to identify the primary opening, while sigmoidoscopy may locate a
proximal internal opening and excludes underlying pathology such as proctitis or neoplasia. If you see either of these
(or fi ndings concerning for either), you need to redirect your
workup and likely perform biopsies, cultures, etc., as appropriate. Colonoscopy or barium enema is indicated in patients
with symptoms of infl ammatory bowel disease, in patients
with multiple or recurrent fi stulas, and in patients who merit
colorectal cancer screening. Anal manometry is normally not
required, but may be useful in women with previous obstetric trauma, elderly patients, a patient with Crohn’s disease or
AIDS or in a patient with a recurrent fi stula [ 5 ]. Preoperative
imaging is used infrequently, with options including fi stulography, CT scanning, endoanal ultrasound, and MRI.
Fig. 21.3 Fistulogram (With permission from Vasilevsky [ 2 ]) ( White
arrows mark fi stula tract)
Imaging Studies
Key Concept: I will use imaging studies in recurrent fi stulas
occasionally when I think it may be helpful to demonstrate
clinically undetected sepsis, to serve as a guide at the time of
the initial surgery, to determine the relationship of the fi stula
tract to the sphincter mechanism, and to reveal the site of
sepsis in a recurrent fi stula.
Fistulography
Key Concept: Although fi stulography may help in select
cases, it is plagued by diffi culties, is invasive, and may result
in the dissemination of sepsis.
Fistulography, which involves cannulation of the external
opening with a small feeding tube or catheter and injection
of water soluble contrast, may be useful in the evaluation of
recurrent fi stulas or in Crohn’s disease where previous surgical forays or disease may have altered anorectal anatomy
(Fig. 21.3 ) [ 6 ]. Contrast is introduced at low pressures to
avoid tissue disruption and allow secondary tracts to fi ll.
Localization of an associated abscess or the level of the internal opening may be diffi cult due to the absence of precise
landmarks. Contrast may refl ux into the rectum wrongly suggesting an extrasphincteric tract with a rectal opening.
Accuracy rates in identifying the internal openings and
extensions have ranged from 16 to 96 % with a false-positive
rate of 12 % [ 6 , 7 ].
336
ab
Fig. 21.4 ( a ) Anal endosonogram ( b ) with hydrogen peroxide. (Courtesy of Dr. Julio Faria) White arrows demonstrate unenhansed fi stula tract.
Black arrows highlight hydrogen peroxide enhansed fi stula tract
D.E. Beck
CT Scan
Key Concept: CT is most helpful to look at surrounding
structures rather than the fi stula itself.
CT scanning performed with intravenous and rectal contrast is a less invasive method to assess the perirectal spaces
and may differentiate an abscess from perirectal cellulitis
[ 2 ]. It does not permit visualization of tracts in relation to the
levators, but may be helpful in assessing the degree of rectal
infl ammation in patients with infl ammatory bowel disease.
Endoanal Ultrasound
Key Concept: Ultrasound often can show you the presence
and extent of the fi stula, though should be interpreted by an
experienced provider.
Endoanal ultrasound can establish the location of the primary opening and the relation of the primary tract to the anal
sphincters, determine if the fi stula is complex, and identify
areas of suppuration [ 8 ]. A study conducted in 2002 using a
10 mHz probe along with injection of hydrogen peroxide was
able to identify the internal opening in 93 % (Fig. 21.4 ) [ 8 ].
Ultrasound is rapid and well tolerated and can be transported
to the operating room for challenging cases. Unfortunately, it
is operator dependent, and scars or defects caused by previous sepsis, surgery, or trauma may confuse ultrasonographic
interpretation [ 10 ].
MRI
Key Concept: MRI is becoming the preferred imaging technique in many centers for recurrent and complex fi stulas.
MRI may be of value in the assessment of patients with
complex fi stulas and in those with anatomic distortion resulting from previous surgery (Fig. 21.5 ). MRI has been found to
accurately delineate the site of the internal opening and the
presence and course of primary and secondary fi stulous
tracts [ 11 ]. It may also signifi cantly decrease recurrence rates
in surgery for recurrent fi stulas [ 12 ]. I fi nd MRI to be useful
in those cases that I feel require imaging and will often use it
as a fi rst modality.
Treatment
General Principles
Key Concept: The principles of fi stula surgery are to eliminate the fi stula, prevent recurrence, and preserve sphincter
function. Success is usually determined by identifi cation of
the primary opening and dividing the least amount of muscle
possible.
Several techniques can help you identify the primary
opening in the operating room:
1. Passage of a probe or probes from the external to the
internal opening or vice versa
2. Injection via a catheter inserted into the fi stula tract of
contrast such as hydrogen peroxide (Fig. 21.6 ) or dilute
methylene blue and noting their appearance at the
dentate line
3. Following the granulation tissue present in the fi stula tract
4. Noting puckering of an anal crypt when traction is placed
on the tract
Patients are educated on the challenges of fi stula manage-
ment and the different approaches available. Depending on
the patient and their anatomy, success has varied from 60 to
90 %. In general, most surgeons prefer to accept a recurrence
21 Fistula-in-Ano
337
Fig. 21.5 Phase array MRI demonstrating the fi stula opening ( black arrow ) and tract ( black arrow head ) (With permission from Vasilevsky [ 2 ])
White arrow demonstrates secondary entension
for hemostasis following insertion of an anal speculum. The
fi stula is assessed to determine its location and relation to the
sphincters using the techniques described above. Taking into
account the characteristics of the fi stula and the patient, several options are available.
Operative Management
Lay-Open Technique (Fistulotomy)
Key Concept: Fistulotomy provides the best success for lowlying fi stulas, though you will have an open wound for a
while that you need to follow-up on.
For simple intersphincteric and low transsphincteric fi stu-
las, a probe is carefully inserted from the external opening
Fig. 21.6 Injection of dilute hydrogen peroxide to identify the internal
opening (Courtesy of W. Brian Sweeney, MD)
through the tract to the internal opening at the dentate line
(Fig. 21.7 ). The tissue overlying the probe is incised with
electrocautery and any granulation tissue and the tract pseu-
doepithelium is curetted or fulgurated. Additional gentle
over injury to the patient or their sphincters. For most surgical procedures the patient is placed in the prone jackknife or
left lateral (Sims’) position following induction of a general
or regional anesthetic. Local anesthesia consisting of mixture of 0.5 % lidocaine or 0.25 % bupivacaine hydrochloride
with 1:200,000 epinephrine is injected along the fi stula tract
probing is used to identify any high blind tracts or exten-
sions, which are unroofed, if found. If you desire, the wound
may be marsupialized on either edge by sewing the edges of
the incision to the tract with a running absorbable suture.
There is no need to insert packing if an adequate unroofi ng
has been accomplished (Figs.
21.8 and 21.9 ).
338
D.E. Beck
Fig. 21.7 Crypt probe running through the fi stula tract
Following the lay-open technique, patients are placed on
regular diets, bulk agents, and non-codeine-containing analgesia. Patients are instructed to take frequent sitz baths to
ensure perianal hygiene. I see them back in the offi ce at
2-week intervals to ensure that healing has occurred from the
depths of the tract. Granulation tissue can be cauterized
using silver nitrate sticks, and cotton-tipped swabs are often
used to probe the depths of the incision to ensure that adequate healing is occurring.
Fistulotomy has the highest success rate but leaves a
wound that must heal by secondary intention. The amount of
sphincter muscle that can be safely divided is a matter of
surgical judgment that takes into account patient characteristics and the specifi cs of the fi stula. In general, division of
muscle distal to the dentate line will not have major alterations in continence. Suprasphincteric fi stulas involve the
entire external sphincter complex as well as the puborectalis
patient incontinent. Thus other methods should be utilized.
Setons
Key Concept: Setons are great for allowing drainage, allowing the tract to fi brose, and preparing the fi stula for a secondary procedure. Cutting setons aren’t used much
anymore.
If the fi stula tract is seen to cross the sphincter muscle at
a high level, the insertion of a seton is an option. A seton may
be any foreign substance that can be inserted into the fi stula
tract to encircle the sphincter muscles. Materials commonly
employed include silk or other nonabsorbable suture material, Penrose drains, rubber bands, or Silastic vessel loops.
Setons may be used in two fashions.
A draining seton is placed through the tract and left
loosely in place to act as a drain to facilitate drainage and
delineate the tract (Fig.
21.10 ). In complex disease, pro-
Fig. 21.8 Technique of laying open. ( a ) Insertion of probe and incision
of tissue overlying probe. ( b ) Curettage of granulation tissue. ( c )
Marsupialization of wound edges (With permission from Vasilevsky [
2 ] )
longed drainage allows resolution of sepsis and provides an
opportunity for additional therapy. Placement of an initial
draining seton has improved the success of subsequent procedures (e.g., the LIFT or suprasphincteric fi stulae), as
described later in this chapter.
Prior to the development of additional surgical options,
when a fi stula involved a signifi cant portion of the sphincter mechanism, a cutting seton was considered. With this
technique, the lower portion of the internal sphincter is
divided along with the skin to reach the external opening
and a nonabsorbable or elastic suture is inserted into the
fi stulous tract. The ends of the suture are tied with multiple
21 Fistula-in-Ano
339
Fig. 21.9 Fistulotomy (Courtesy of W. Brian Sweeney, MD)
Fig. 21.11 Diagram of a cutting seton (With permission from
Vasilevsky [
2 ] )
Fig. 21.10 Silastic vessel loop draining seton in place
knots to create a handle for manipulation (Figs. 21.11 and
21.12 ). The cutting seton was traditionally tightened at
regular intervals to slowly cut through the sphincter. This
allows the tract to become more superfi cial, converting a
high fi stula into a low one. The proximal fi stulotomy subsequently heals by stimulating fi brosis behind it. This prevents separation or retraction of the sphincter muscle. The
seton also allows delineation of the amount of remaining
muscle that may be divided at a second operation several
weeks later. The technique is very uncomfortable for the
patient, and with the availability of other options, cutting setons are rarely used. A recent extensive literature
search suggested abandoning the use of cutting setons
because of sphincter damage and incontinence rates
approaching 12 % [ 2 ].
Fig. 21.12 Cutting seton in place (Courtesy of W. Brian Sweeney,
MD)
Anorectal Advancement Flap
Key Concept: Anorectal advancement fl aps provide a good
option for diffi cult and recurrent fi stulas. Ensure your fl ap is
well vascularized by making it wide enough, including some
of the underlying muscle and mobilize enough to make it
tension-free.
The traditional laying-open technique is often inappropriate for anterior fi stulas in women, in patients with infl ammatory bowel disease, in patients with high transsphincteric and
suprasphincteric fi stulas, as well as in those with previous
multiple sphincter operations and multiple and complex fi stulas. For these patients, an anorectal advancement fl ap has
been advocated (Figs. 21.13a–d and 21.14 ) [ 14 ]. Advantages
340
D.E. Beck
Fig. 21.13 Anorectal advancement fl ap. ( a ) Transsphincteric fi stula-
in-ano. ( b ) Enlargement of external opening and curettage of granula-
tion tissue, ( c ) mobilization of fl ap and closure of internal opening, ( d )
of this technique include a reduction in the duration of healing, reduced associated discomfort, lack of deformity to the
anal canal, as well as little potential additional damage to the
sphincter muscles since no muscle is divided [ 2 ].
Following preparation and positioning, the fi stula tract
is identifi ed with a probe and either cored out or curetted.
The internal opening is identifi ed and excised and the external opening is enlarged to allow for drainage. A full-thickness fl ap of rectal mucosa, submucosa, and part of the
internal sphincter is raised. The residual internal opening is
closed with absorbable suture. The fl ap is then advanced 1
cm below the internal opening. The tip of the fl ap containing the fi stulous opening is excised, and the fl ap is sewn
into place with absorbable sutures ensuring that the mucosal
suturing of fl ap in place covering internal opening (With permission
from Vasilevsky [
2 ] )
and muscular suture lines do not overlap. The base of the
fl ap should be twice the width of the apex to maintain good
blood supply. Successful results have reported in over 90 %
of patients [ 15 ]. Factors associated with poor outcomes
include Crohn’s disease and steroids [ 16 ]. The fl ap is a
great option for recurrent or diffi cult fi stula-in-ano, but you
need to ensure your technique allows for great mobilization
and preservation of the blood supply to optimize your
success.
Fibrin Glue
Key Concept: With time and experience, fi brin glue has had
low rates of incontinence but high rates of failure and
recurrence.
21 Fistula-in-Ano
341
Fig. 21.14 Completed anorectal advancement fl ap (Courtesy of W.
Brian Sweeney, MD)
Fig. 21.15 Injection of fi brin glue down a fi stula tract (Courtesy of W.
Brian Sweeney, MD)
The use of fi brin glue as a primary treatment alone or in
combination with an advancement fl ap was appealing since
it is a simple, noninvasive approach that avoids the risk of
incontinence associated with fi stulotomy. In the case of failure, it may be repeated several times without jeopardizing
continence. As with fi stulotomy, the fi stula tract along with
its internal and external openings is identifi ed and curetted
(with curettes or fl exible brushes). Fibrin glue is injected into
the fi stula tract through a Y connector so that the entire tract
is fi lled and the glue can be seen emerging from the internal
opening (Fig.
drawn so that the entire tract is fi lled (Fig.
21.15 ). The injecting catheter is slowly with-
21.16 ).
Enthusiasm generated because of initial short-term success
rates of 70–74 % has been tempered due to delayed fi stula
recurrence despite initial apparent healing [
17 – 19 ]. Slightly
better results were obtained with a 2-stage approach consisting
of seton placement followed by glue injection at a second stage.
Although the exact mechanisms responsible for failure have
not been entirely appreciated, it has been suggested that curettage may not adequately remove all granulation or epithelialized tissue thus failing to provide the correct environment for
the glue to work [
20 ]. Other adverse factors shown to infl uence
healing include the presence of a short tract which may make it
easier for the fi brin glue plug to become dislodged as well as
the presence of a cavity on endoanal ultrasound [ 21 ]. The latter
was associated with a complication of perianal abscess since
the tract may not have been entirely fi lled with glue [ 22 ]. Fibrin
glue is associated with a low incontinence rate as well as a
disappointing low cure rate and not used much anymore.
Anal Fistula Plug
Key Concept: Plugs provide an option for sphincter preservation, although recurrence and failure rates are 40–60 %.
Two bioprosthetic plugs are currently available to treat anal
fi stulas. The Biodesign® anal fi stula plug (lyophilized porcine
intestinal submucosal, Cook Biotech, West Lafayette, IN) and
the Gore® Bio-A fi stula plug (synthetic bioabsorbable, W L
Gore, Flagstaff, AZ) provide a scaffold for colonized by host
tissue cells, blood vessels, and connective tissue.
Following preparation and positioning, the internal and
external openings are delineated. A probe is gently passed
from the external to the internal opening to confi rm the position of the tract and facilitate insertion of the plug.
Debridement or curettage of the tract should not be performed. A seton should be used temporarily if there is acute
infl ammation or drainage. A 2-0 suture is placed through the
tapered end of the plug and the ends of this suture are
attached to the fi stula probe at the primary opening. The
suture is pulled from the primary opening, through the fi stula
tract to exit at the secondary opening. For patients with a
“horseshoe” fi stula, an incision may be made over the fi stula
tract distal to the anal verge to create a secondary opening
that the ends of the suture are brought through. With gentle
traction on the suture, the plug is pulled into the primary
opening of the fi stula until it is snug but not forced tightly.
Excess plug is removed by transecting the plug at the level of
the primary opening. The plug is secured in the primary
opening using a 2-0 absorbable suture placed in a fi gure of 8
fashion with the suture crossing through the center of the
plug and incorporating a generous portion of the sphincter
mechanism on both sides. Any plug protruding through the
secondary opening is also excised. The distal end of the plug
is not sutured to the fi stula tract and the distal opening is left
open for drainage (Fig.
21.17 ). Patients are advised to avoid
vigorous physical activity for 2 weeks after plug placement
to minimize the chance of plug dislodgement. No dietary
restrictions are necessary nor are topical antibiotics
indicated.
342
Fig. 21.16 Endoscopic view of
fi brin glue fi lling the internal
opening. The internal opening can
be seen in the left upper picture as
the dark area at ~7o’clock, with
subsequent images showing the
fi brin glue fi lling this opening
(Courtesy of W. Brian
Sweeney, MD)
D.E. Beck
Fig. 21.17 Anal fi stula plug (Courtesy of David Armstrong, MD,
Atlanta, GA)
As with many of these alternative techniques, initial
results were successful [
23 , 24 ]. Unfortunately, subsequent
experience has been less successful with healing rates averaging 40–60 %. Contraindications for the use of the plug
include fi stulas with a persistent abscess cavity or infection,
allergy to porcine products, and inability to identify both the
external and internal openings. The latter constitutes an
absolute contraindication for use of the plug. The plug is useful in certain situations of failure or recurrence or in people
with borderline continence that you want to ensure no damage to the muscle occurs.
LIFT Procedure
Key Concept: The LIFT identifi es and divides the fi stula tract
in the intersphincteric space. Readying the tract with use of
a seton to allow for fi brosis will aid in success.
21 Fistula-in-Ano
343
Fig. 21.18 LIFT procedure. Dissection of the fi stula tract in the intersphincteric plane
Recently a new sphincter-sparing technique has been
introduced called the ligation of the intersphincteric fi stula
tract (LIFT) procedure [ 25 ]. This technique relies on the
secure closure of the internal opening and removal of the
infected cryptoglandular tissue in the intersphincteric space.
Patients with early fi stulous abscess in which the intersphincteric tract is not well formed and those with high internal
openings are less suitable for this technique.
After preparation and positioning an anoscope is inserted
into the anal canal and the internal opening is identifi ed. A
probe is gently passed through the fi stula tract. A 1.5–2.0
cm curvilinear incision is made at the intersphincteric
groove overlying the fi stula tract and cautery is used to dissect into the intersphincteric plane. The intersphincteric
tract that contains the probe is dissected (Fig. 21.18 ),
divided, and ligated next to the internal opening with an
absorbable suture. The residual tract distal to the suture is
also ligated. Tract division may be confi rmed by injection or
probing of the external opening and granulation tissue may
be curetted. The incision is closed with 3-0 absorbable
suture (Fig. 21.19 ).
Initial reports in the literature include success rates of
58–94 % [ 25 , 26 ]. The exact place where the LIFT fi ts into
the algorithm for fi stula management remains to be seen.
Some surgeons are using the LIFT more and more as a primary option (following seton placement) for all high and
complex fi stulae that cannot be managed with a fi stulotomy,
while others reserve this procedure for failures or recurrences. While this is a promising technique, more experience
and longer-term follow-up data is going to prove valuable.
Fistulectomy
Key Concept: Removal of the tract entirely should (in general) not be performed.
Fig. 21.19 Completed LIFT procedure
Excision of the fi stula or fi stulectomy is avoided as it produces larger wounds with prolonged healing time, a greater
separation of muscle ends, a greater risk of injuring or excising underlying muscle, and a subsequent greater risk of
incontinence [ 14 , 27 ].
Dermal Flaps
Key Concept: Using the perineal skin for a fl ap, instead of
anorectal mucosa, is useful for distal non-healing fi stula.
Another option to treat transsphincteric fi stulas without
division of muscle involves the use of a dermal fl ap. This
technique closes the internal opening using a variety of skin
fl aps, such as sliding (House) or island fl aps. It is helpful in
distal fi stulas in which a mucosal advancement fl ap would
produce an ectropia and in patients who have failed other
techniques. Success has been reported as 77 % [ 28 ].
Results
My Approach
The author’s preference is to select a fi stulotomy for simple
low fi stulas. For more complicated fi stulas, I would consider
a draining seton if there is infection or infl ammation present
or either a plug or LIFT for the fi rst attempt. Recurrences are
offered a LIFT (if a plug was used previously or the tract is
suitable for a LIFT) or an advancement fl ap. Next, for continued failures, a Martius fl ap with or without proximal
diversion.
Complications
Key Concept: Similar to any procedure, both early and late
complications can be expected in a small percentage of
344
Table 21.2 Results of fi stula surgery
Author Year No. of patients Recurrence % Incontinence %
Marks and Ritchie [
Vasilevsky and Gordon [
Van Tets [
Sangwan [
Garcia-Aguilar et al. [
Mylonakis [
Malouf [
Westerterp [
a
3 % solid stool, 17 % liquid stool, 25 % fl atus
b
0.7 % solid stool, 2.0 % liquid stool, 3.3 % fl atus
d
0 solid stool, 6.0 % soiling, 3,0 % gas
29 ] 1994 19 – 33.0
32 ] 1994 461 6.5 2.8
35 ] 2002 98 4.0 10
30 ] 1977 793 – 3, 17, 25 a
31 ] 1985 160 6.3 0.7, 2.0, 3.3 b
33 ] 1996 293 7.0 42.0
34 ] 2001 100 3.0 0, 6.0, 3.0 c
36 ] 2003 60 0 50
D.E. Beck
patients. Using proper technique and placing the patient on
a postoperative bowel and wound regimen will help to minimize these complications .
Early postoperative complications that have been reported
following fi stula surgery include urinary retention, hemorrhage, fecal impaction, and thrombosed external hemorrhoids, which were found to occur in less than 6 % of cases
[ 2 ]. Later complications such as pain, bleeding, pruritus, and
poor wound healing have been reported in ~9 % of patients
[ 14 ]. Anal stenosis may occur and is usually the result of
loose stools allowing healing of the anal canal by scar contracture. Mucosal prolapse due to extensive division of
sphincter muscle may also occur and can be treated by band
ligation, sclerosis, or excision [ 14 ]. With attention to both
operative detail and postoperative follow-up, these complications can be reduced to a minimum.
Incontinence
Key concept: Incontinence after fi stulotomy depends both on
the amount of muscle divided at operation and on preexisting
sphincter damage and scarring of the anal canal.
Minor disorders of continence following fi stulotomy have
been reported to range from 18 to 52 %, while soiling and
insuffi ciency have been reported in as many as 35–45 % [ 29 ]
(Table 21.2 ). The occurrence of continence disorders has
been found to be related to the complexity of the fi stula and
to the level and location of the internal opening [ 29 ].
Patients with complicated fi stulas, high openings, posterior openings, and fi stula extensions have been found to be at
higher risk [ 29 ]. In the treatment of complicated fi stulas and
those with high openings, more muscle is divided, thus
decreasing anal pressures, while posterior fi stula wounds
have been associated with higher rates of incontinence
because of their more circuitous routes [ 29 ]. Drainage of
extensions may accidentally damage small nerves and create
more scar tissue around the anorectum [
29 ]. If the edges of
the fi stulotomy wound do not approximate precisely, the anus
may be unable to properly close, resulting in intermittent
leakage of gas and stool [
37 ]. In addition to these factors,
impaired continence was associated with increasing age [ 30 ]
and female gender [ 29 , 30 ]. The latter is probably the result of
partial anal sphincter disruption and/or traction injury to the
pudendal nerves sustained during vaginal delivery [ 30 ].
Although excellent results employing a seton have been
reported [ 38 ], its use does not protect against the develop-
ment of impaired continence [ 29 ]. Minor continence disor-
ders were reported in 73 % [ 29 ] while Williams [ 39 ] reported
minor disturbances in 54 %. Parks [ 40 ] found that minor
incontinence occurred in 39 % with the two-stage approach
versus 17 % when only the fi rst stage was performed and the
seton was removed rather than dividing the muscle. Major
fecal incontinence was reported as 6.7 % in a review of several series [ 30 ]. The degree of incontinence is thought to be
infl uenced by the patient’s preoperative state of control as
well as to how the anal wound heals [ 30 ]. Analysis of data
compiled in a recent literature search found that a 12 % rate
of incontinence with the rate increasing as the location of the
internal opening moved more proximally [ 13 ].
Excellent results with respect to continence have been
reported with the use of the advancement fl ap, although
recent reports have observed disturbances in continence in
9–35 % attributed to overstretching of the sphincters by selfretaining retractors [ 16 , 41 , 42 ]. Disruption of the internal
sphincter also occurs if some internal sphincter fi bers are
developed with the fl ap [ 43 ].
As would be expected, continence is unaffected with the
use of fi brin glue and the fi stula plug. In a study that looked
at changes in anorectal morphologic and functional parameters after fi stula surgery, it was found that fi stulotomy and
advancement fl aps were most associated with changes in
internal anal sphincter defects with decreased resting and
squeeze pressure on manometry noted after fi stulotomy
while rectal advancement fl aps were associated with decrease
in resting pressure [
44 ]. It therefore behooves you as the sur-
geon to recognize preexisting sphincter defects by endoanal
ultrasound prior to embarking on fi stula surgery.