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50
ab
P. Sheikh and P. Bajaj
d
c
Fig. 5.3 Classifi cation of fi stula-in-ano. ( a ) Low inter-
sphincteric fi stula-in-ano causing a perianal abscess. ( b )
Transsphincteric fi stula causing an ischiorectal abscess.
On examination, fi ndings vary according to anatomic location of anorectal abscess.
Examination under anesthesia may be required in
some cases. Perianal and ischiorectal abscess will
have erythema, swelling, tenderness, and fl uctuation over their respective sites. Intersphincteric
or submucous abscess may not have any visible
external manifestation despite patient’s complaint of severe excruciating anal pain. Digital
rectal examination may not be possible because
of severe tenderness. However, digital examination, if possible, will demonstrate tender fl uctuant
mass in these cases. Evaluation under anesthesia
or MRI maybe required in cases where digital rectal examination is not possible or the diagnosis is
(c ) High intersphincteric fi stula causing a supralevator
abscess. ( d ) Extrasphincteric fi stula
in doubt. Supralevator abscess represents upward
extension of intersphincteric abscess.
5.5.2 Anal Fistulas
A fi stula-in-ano represents the chronic phase of
ongoing anorectal sepsis. A previous history of
anorectal abscess drained either spontaneously or
surgically can usually be elicited. Patients often
report a cyclical pattern of pain, swelling, and
drainage. Moisture can cause skin irritation,
excoriation, and pruritus. Crohn’s disease should
be excluded in patients with history of chronic
diarrhea or abdominal pain.
5 Perianal Sepsis and Fistula
a
b
c
Fig. 5.4 ( a ) Recurrent fi stula showing internal and external openings. ( b , c ) Water-can perineum with recurrent com-
plex fi stulas
51
Physical examination usually identifi es one or
more external openings with or without granulation tissue and a surrounding scar. Occasionally,
the external opening may be subtle and appreciated only after closer inspection of an indurated
area. Uncommonly, the patient may present during the phase where the external opening has
temporarily closed. Palpation may elicit tenderness, expression of pus, and a fi brotic cord
extending toward the anus. The external tracts are
usually not felt during its entire course, unless it
is a very low fi stula. Several external openings
may be present because of branching complex
fi stulous tracts, a condition called as wateringcan perineum. It is generally not recommended to
do probing of the fi stula track in the offi ce setting, but digital anorectal examination, anoscopy,
and proctoscopy may help discover the internal
opening (Fig. 5.4b ) and the presence of any other
rectal disease. The internal opening is often seen
at the dentate line which is consistent with cryptoglandular theory of anorectal sepsis. An
enlarged papilla is often present at the site of the
internal opening. Most common site for internal
opening is posterior midline as most anal glands
are located posteriorly. The intersphincteric tract
may be felt as a submucosal induration on digital
rectal examination.
In 1900, Goodsall described a simple rule
that uses the location of the external fi stula
opening to predict the location of the internal opening. Fistulas with external openings
anterior to the anterior half of the anus, usually track in a radial fashion directly into the
anal canal (Fig. 5.5 ). Fistulas with an external
opening in the posterior half of the anus usually track in a curvilinear fashion to originate
from the posterior midline. Exception to this
rule includes multiple external openings, and
external opening which is present anteriorly,
more than 3 cm. from the anal verge. In most of
these cases, the internal opening will be in the
midline posteriorly.
Ciroco and Reilly found that Goodsall’s rule
was inaccurate in patients with anterior external
opening because almost 71 % of these fi stulas
52
P. Sheikh and P. Bajaj
a
b
Fig. 5.5 Goodsall’s rule
have internal opening in midline anteriorly
(Cirocco 1992 ). The Goodsall’s rule also fails in
cases of fi stula with associated carcinoma or
Crohn’s disease (Fazio 1987 ). The Goodsall’s
rule is not accurate in a fair number of patients
and cannot be relied upon in all the cases.
5.5.3 Special Studies
5.5.3.1 Sigmoidoscopy and Colonoscopy
Sigmoidoscopy should be performed in all
patients with symptoms suggestive of anal fi stula
in order to rule out other pathologies like proctitis
or neoplasia. Presence of symptoms suggestive
of infl ammatory bowel disease or neoplasia
necessitates need for full colonoscopy.
5.5.3.2 Fistulography
Contrast material-enhanced fi stulography was
the fi rst imaging modality used. In fi stulography, the external opening is catheterized with a
fi ne cannula, and a water-soluble contrast agent
is injected gently to defi ne the fi stula tract
(Fig. 5.6 ). Fistulography was the most widely
used imaging modality. However, it was of limited sensitivity due to its poor localization of
the internal opening, absence of precise anatomic landmarks, and lack of direct demonstration of the sphincter complex and levator ani
sling. There was a high probability of missing
Fig. 5.6 ( a ) Dye injected through distal opening on the
thigh. ( b ) Fistulogram through the external opening show-
ing communication with anal canal
the secondary fi stulous tracks, due to frequent
non-fi lling of the side branches with subsequent high rates of postoperative recurrence
(SteveHalligan and JaapStoker 2006 ; Jones
Jennifer and Tremaine William 2005 ; Kuijper
and Schulpen 1985 ). The current use of fi stu-
lography may be limited to fi nding out the
presence or absence of fi stula, in patients with
external opening situated at a distant site, or in
a nonhealing postoperative wound. The dye
entering the anal canal will confi rm the presence of a fi stula. The presence of a long tract or
a tract coursing toward the anal canal without
5 Perianal Sepsis and Fistula
53
Fig. 5.8 Three-dimensional endoanal USG
peroxide highlight the track and may help to locate
the site of the internal opening. However, insuffi cient penetration of the ultrasound beam beyond
the external sphincter, especially with high-fre-
Fig. 5.7 Endoanal USG showing an intersphincteric
abscess
quency transducers, limits the ability to image
ischioanal and supralevator infections, with the
result that extensions from the primary tract may be
missed at endosonography. In patients with recurentering it may be suggestive of a fi stulous
tract. Even for these cases, there are better
imaging modalities available.
rent disease, anal endosonography may not be reli-
able, because of its inability to distinguish infection
from fi brosis (Choen et al.
1991 ). Three-
dimensional ultrasonography may be more useful
5.5.3.3 Endoanal Ultrasonography
in detecting smaller lesions (Fig. 5.8 ).
Anal endosonography developed by Clivev
Bartram was the fi rst technique to directly depict
the anal sphincter complex in detail (Law and
Bartram 1989 ). It is simple, rapid, and well toler-
ated by patients. Because of its ability to demonstrate the presence and extent of anal sphincter
disruption, the technique has attracted considerable attention (Sultan et al.
1993 ) (Fig. 5.7 ). The
internal sphincter is visualized as a hypoechoic
ring encircling the anal canal, whereas the external sphincter is of mixed echogenicity. The
5.5.3.4 Computed Tomography (CT) Scan
Computed tomography with rectal and intravenous contrast had been used for evaluation of
fi stula-in-ano; however, it did not gain popularity
because of poor visualization of levators and
sphincter complex. At present, CT scan is indicated in patients with suspected supralevator
abscess or high-complex fi stula to rule out associated pelvic pathology (Fig.
5.9 ).
intersphincteric space and longitudinal muscle lie
between these and are of mixed echogenicity and
are easily identifi ed by using modern 10-MHz
transducers (Frudinger et al. 2002 ).
Internal opening of the fi stulous tract and intersphincteric fi stulas is usually very well visualized
at anal endosonography. Transsphincteric fi stulas
are revealed by tracts that cross the external sphincter to reach the ischioanal fossa. Extensions from
primary tract are revealed as hypoechoic fl uid
collections. The gas refl ections from hydrogen
5.5.3.5 Magnetic Resonance Imaging (MRI)
MR imaging is the most accurate method for
determining the presence and course of anal fi stula (Lunniss 1992 ). The success of MR imaging
for preoperative classifi cation of fi stula-in-ano is
a direct result of the sensitivity of MR for tracts
and abscesses combined with high anatomic precision and ability to image in surgically relevant
planes (Fig. 5.10 ). Endoanal coil provides
54
ab
Fig. 5.9 CT scan. ( a , b ) Reconstructed CT scan showing a supralevator tract
P. Sheikh and P. Bajaj
Fig. 5.10 Endocoil MRI showing an intersphincteric
abscess
excellent anatomic detail of the anal sphincters.
However, because of its limited fi eld of view and
limited accuracy in complex supralevator types,
it has not become very popular. The body coil or
the pelvic surface coil is more frequently used for
imaging the pelvis in fi stula patients
(SteveHalligan and JaapStoker et al. 2006 ).
Spencer and colleagues independently classifi ed
37 patients into those with simple or those with
complex fi stulas on the basis of MR imaging and
EUA and found that MR results were better predictors of outcome, with positive and negative
predictive values, respectively, of 73 and 87 %
for MR and 57 and 64 % for EUA (Spencer et al.
1998 ). In a study by Beeets-Tan et al., preopera-
tive MRI had a sensitivity and specifi city of
100 % and 86 %, respectively, for identifi cation
of fi stulous tract and sensitivity and specifi city of
96 % and 90 % for preoperative detection of
internal opening (Beets Tan et al. 2001 ).
Intravenous contrast studies are more specifi c
and can attain similar results of local MRI fi stulogram. So, it should be routinely included in MRI
protocols of anal fi stula examination, even with
no abscess or collection seen at the precontrast
images. Color Doppler can help to check patency
of the fi stulous track and can be added as complementary noninvasive investigation.
5.5.3.6 Anorectal Manometry
The role of anorectal manometry to diagnose fi stula is very limited. It may be more useful in
managing fi stulas with preoperative incontinence
or coexisting obstructed defecation syndrome. It
may also prove to be useful in cases of medical
litigation if the anal pressures are documented
before and after surgery.
5 Perianal Sepsis and Fistula
55
5.5.3.7 Fistuloscopy
Anorectal fi stuloscopy using fl exible uretroscope
is a new modality under evolution that is useful
intraoperatively to indentify primary fi stulous
opening, multiple, complex tracts or iatrogenic
tracts (Johnson et al. 2005 ). It can be a promising
tool in diagnosis and management of complex
fi stula in times to come.
5.6 Treatment
5.6.1 Anorectal Abscess
Perianal abscess is a surgical emergency and
should be treated by urgent incision and drainage
(Whiteford 2005 ). Depending on the condition
of the patient and location of the abscess, drainage can be done either as an outpatient procedure
or may be done under anesthesia in an operating
room. Conditions such as cellulitis without fl uctuation, failed drainage in the offi ce, abscesses
with symptoms and signs of sepsis, or extensive
abscesses with supralevator extension are more
appropriately treated in the operating room, where
a thorough examination under anesthesia can
ensure optimal diagnostic evaluation and drainage. Although incision and drainage is effective
in resolving the acute abscess, the patient is at
risk for developing chronic anal fi stula or recurrent perianal sepsis or both. These conditions
occur in 35–50 % of patients after a fi rst-time
perianal abscess (Hamadani et al.
smoking history, perioperative administration of
antibiotics, and HIV status are not risk factors for
fi stula formation or recurrence of perianal sepsis (Hamadani et al. 2009 ). The drainage should
be done as close to the anus as possible in order
to shorten the length of any subsequent fi stulous
tract. Mechanical disruption of loculi around
abscess cavity may cause injury to sphincter complex or the pudendal nerve and hence should be
done carefully in order to ensure adequate drainage of all pus. Routine addition of antibiotics has
not been shown to improve healing time or reduce
recurrence rate (Llera and Levy 1985 ; Stewart
et al. 1985 ; Macfi e and Harvey 1977 ). Antibiotics
2009 ). Gender,
should be considered for patients with high-risk
conditions such as diabetes, immunosuppression,
extensive cellulitis, prosthetic devices, and valvular heart diseases (Whiteford
1997 ). After successful drainage, pain relief is
usually immediate. Postoperatively, patients are
advised to use sitz bath, laxatives, and analgesics.
Bleeding and drainage usually subside within a
few days. The wound heals over a matter of few
weeks. Follow-up is encouraged because acute
abscesses occur in 10 % and of chronic fi stula-inano occurs in up to 50 % of patients (Vasilevsky
and Gordon 1984 ).
The patient is placed in the prone jackknife,
left lateral, or in lithotomy position, and the area
surrounding the abscess cavity is adequately
painted and draped. Patient may be given general
anesthesia or perianal fi eld block as per location
of abscess. A stab incision is made with an 11 or
15 number blade at the point of maximum fl uctuation in closest proximity to the anal verge.
Larger cavities may require digital or hemostatassisted exploration to break up any undrained
abscesses. In addition to adequate drainage, one
should endeavor to prevent acute recurrence of an
abscess by either excising the overlying skin or
by inserting drainage catheter. Either of these
techniques will allow any undrained pus to be
expelled and decrease the chance of acute recurrences (Isbister 1987 ; Read and Abcarian 1979 ).
The patient is advised pain medications and a
follow-up appointment in 1–2 weeks at which
point the drainage catheter is removed. Antibiotics
are prescribed if indicated.
Intersphincteric, supralevator, and deep postanal abscesses are best treated in the operating
room where a thorough exam can be performed.
For intersphincteric abscesses, the internal
sphincter is divided from its lower end to the dentate line and hemostasis is achieved. If a supralevator abscess is a result of upward extension of
an intersphincteric abscess, the abscess should be
drained directly into the rectum (Fig.
However, if it is a result of an ischioanal abscess,
it should be drained via the ischioanal fossa
(Figs. 5.12 and 5.13 ). Supralevator abscesses that
are caused from extrapelvic diseases such as
2005 ; Dajani et al.
5.11 ).
56
P. Sheikh and P. Bajaj
Fig. 5.11 Drainage of intersphincteric abscess through
the internal opening
Fig. 5.13 Route of drainage of ischiorectal and perianal
abscess
Fig. 5.12 Diagrammatic representation of drainage of
intersphincteric abscess through internal opening
Crohn’s, diverticulitis, or appendicular abscesses
may be initially drained via the rectum or the
ischioanal fossa. However, pathology of the
offending organ must be addressed (Gordon and
Nivatvongs 1999 ).
5.6.2 Horseshoe Abscess
The horseshoe abscess is caused by an infected
anal gland located in the posterior midline of the
anal canal. The presence of the dense overlying
anococcygeal ligament prevents the direct downward expression of an abscess. As a result, the
suppuration follows the path of least resistance
Fig. 5.14 Horseshoe abscess
laterally into ischiorectal fossa, hence the term
“horseshoe” (Fig. 5.14 ). Treatment requires
unroofi ng of the abscess cavity through the overlying anococcygeal ligament along with counter
drainage of the lateral extensions. Placement of a
draining (loose) seton may prevent premature
skin closure, avoid an acute abscess recurrence
by providing a route of egress for the infection,
and facilitate fi brosis of the fi stula tract.
5 Perianal Sepsis and Fistula
57
5.6.3 Abscess and Primary Fistulotomy
Fistulotomy performed at the same sitting as
incision and drainage of a perirectal abscess is
termed a “primary” or “synchronous” fi stulotomy. Doing a primary fi stula surgery along
with drainage of the anorectal abscess has been
a matter of much debate. The fear of causing
incontinence and the fact that more than half of
all drained abscesses may develop a fi stula have
resulted in condemning a primary surgery for
an anorectal abscess. However, a recent systematic review comparing outcome after primary
fi stula surgery done along with drainage of
perianal abscess, compared with drainage
alone, showed that fi stula surgery with abscess
drainage signifi cantly reduced recurrence or
persistence of abscess/fi stula or the need for
repeat surgery (Malik et al. 2010 ). Statistically,
there was no signifi cant evidence of incontinence following fi stula surgery with abscess
drainage. This intervention may be recommended in carefully selected patients. Another
meta-analysis comparing the two procedures
concluded that there was no conclusive evidence if simple drainage or sphincter-cutting
procedure is better in the treatment of anorectal
abscess–fi stula (Quah et al. 2006 ). A long-term
follow-up seems not to infl uence the results of
fi stulotomy group and confi rms that fi stulotomy
is an effi cient and safe treatment of anal abscess
with good long-term results (Benjelloum et al.
2013 ). An exception is a high fi stula, where fi s-
tulotomy may be associated with a risk of
recurrence and incontinence.
5.6.4 Fistula-in-Ano
Surgery is the preferred modality of treatment
for patients with in ano. With delay in treatment,
a simple fi stula can progress to chronic abscess
or to a complex fi stula and hence the need for
timely intervention. There has been no consensus on surgical options for treating it. The existing options have not yielded satisfying results,
hence the need to discover new options.
Recurrence and incontinence are the two major
paradoxical factors which a surgeon fears and
drives him/her to tilt on one side or the other.
Surgery for fi stula can be performed under general, regional, or local anesthesia with sedation.
Patient is placed either in lithotomy or prone
jackknife position, depending on patient characteristic, location and extent of fi stula, and the
surgeon’s preference.
5.6.4.1 Advancement Flap
Advancement fl aps have been used to close the
opening in fi stula since long. The success with
advancement fl ap as a stand-alone procedure
ranges from 59–72 % (Mizrahi et al. 2002 ;
Sonoda et al. 2002 ). Crohn’s fi stulas have a lower
success rate. Repeating this procedure multiple
times can further increase the success rate to as
much as 90 % (Mitalas et al. 2007 ; Jarrar and
Church 2011 ). Continence can deteriorate in
9–14 % of patients after this procedure.
Advancement fl aps consist of mucosa, submucosa, and part of the internal sphincter. The fl ap is
lifted, edge of the fl ap containing internal opening. The underlying fi stulous tract is excised up
to the level of the internal sphincter. Here, the
tract is transfi xed. The fl ap is then advanced and
sutured to close the internal defect. The outer part
of the track can be curetted. In the last couple of
years, there have been many articles comparing
treatment with advancement fl aps and anal fi stula
plug. A meta-analysis comparing the two methods has revealed equivalent success rates, but
overall results were in favor of the fi stula plug.
Later, it was associated with decreased risk of
incontinence, less postoperative pain, faster healing, and a superior quality of life (Fig.
(Leng and Jin 2012 ).
5.15 )
5.6.4.2 Fibrin Glue
Fibrin glue has been used as a sphincter-sparing
approach for the treatment of anal fi stula for 2
decades. The mixture of fi brinogen and thrombin is injected into the fi stulous tract after it has
been curetted out thoroughly (Figs. 5.16 and
5.17 ). It activates fi brinogen-forming fi brin clot.
The resulting coagulum plugs the fi stulous tract
completely. Migration and activation of
58
P. Sheikh and P. Bajaj
Fig. 5.15 Advancement fl a p
Fig. 5.17 Fibrin glue being injected
have been reported in 3 % patients. Sometimes, it
can create more complicated fi stulous tracts. It is
more successful for simple and low anal fi stula
and should be reserved for patient unfi t for surgery. The procedure is contraindicated in presence of sepsis. Recurrence is reduced by
two-stage operation, tackling side tracks as well,
and closing the internal opening by skin or mucosal fl aps.
Fig. 5.16 Fibrin glue material and equipment used
fi broblasts form a collagen network. Glue is
injected through a catheter part, and patient is
immobilized under general anesthesia for about
15 mts for fi xation.
The advantage of this procedure is that it is
simple to use, has minimal morbidity, and should
not affect later treatment options in the event of
its failure. The success rates are however very
diverse and low. A paper, which reviewed studies
from 1966 to 2004, showed a success rate varying from 0 to 100 % (Hammond et al. 2004 ).
Subsequent papers have revealed success rate
between 38–41 % for simple fi stulas and much
lower rate for complex fi stula (Yeung et al. 2010 ;
Loungnarath et al. 2004 ). Septic complications
5.6.4.3 Seton
A seton is a thread of nylon, Prolene, rubber, or
other material that is nonabsorbable and is placed
through the fi stula tract with the purpose of keeping it open for a certain period of time. It was fi rst
described by Hippocrates in ancient Greece
(draining seton).
It is based on the principle that no fi stula will
close permanently if the “feeding” abscess or
infection does not drain completely. After a partial excision of a fi stula, the external (skin) orifi ce
has a tendency to close much faster than the internal orifi ce. Thus, early closure of the external fi stula orifi ce will “trap” infection inside the fi stula
track and will result in a recurrent abscess/infection.
By keeping the fi stula track patent and draining
for a long time, seton allows the gradual complete
drainage and clearing of the infection. A seton
may stay in place for a long time (3–12 months or
5 Perianal Sepsis and Fistula
a
b
59
c
Fig. 5.18 Cutting seton. ( a ) Sphincter complex dissected and fi stula excised. ( b ) Seton tightened. ( c ) Seton in place
(post-op)
more). Although it may be slightly uncomfortable for the fi rst few days, most patients get used
to it very quickly and are not even aware of its
presence.
Setons have been placed in anal fi stulas either
for the purpose of cutting the sphincter (cutting
seton) in a phased manner (Fig.
5.18 ) or as drain-
ing setons to drain sepsis, promote fi brosis, and
mature the tract for drainage and defi nitive surgery. It is indicated in complex and recurrent fi stula, high transsphincteric fi stula, elderly patients
with chronic diarrhea and Crohn’s fi stula, immunocompromised patients, and female patients
with anterion fi stula. Seton placement is
recommended to reduce postoperative fecal
incontinence, but interestingly, a great range of
functional impairment after surgery has been
published. A systematic review of articles related
to seton use has revealed a recurrence rate of 5 %
in patients in whom the internal sphincter was
preserved. In those patients where the internal
sphincter was not preserved, the recurrence rate
was only 3.0 % (Vial et al. 2010 ). The overall
fecal incontinence rate was 5.6 % in the former
group and as high as 25.2 % in the latter group.
Drawbacks of seton are reduction in anal pressure, retractable deformities of anal canal, and
long healing period. Average cutting time is
14–20 weeks.
Draining setons are usually not placed as a
stand-alone procedure, but either combined with
closure of the internal opening (simple closure or
fl ap closure) or are a prelude to another procedure like LIFT or fi stula plug. Staged draining
setons may not be very effective in horseshoe fi stula (Lim et al. 2012 ).