DR.SEFEEN SAFE ATTIA
SOHAG TEACHING HOSPITAL
A fistula is an abnormal connection betweenA fistula is an abnormal connection between
two epithelial surfaces.two epithelial surfaces.
The term fistula is derived from the LatinThe term fistula is derived from the Latin
meaningmeaning ““pipe, or flute.pipe, or flute.””
An anal fistula is a tract which usuallyAn anal fistula is a tract which usually
communicates an infected anal gland to acommunicates an infected anal gland to a
secondary opening in perianal skin, which issecondary opening in perianal skin, which is
lined with granulation tissue.lined with granulation tissue.
Cryptoglandular disease (anorectal abscesses )Cryptoglandular disease (anorectal abscesses )
is responsible for 90% of fistula-in-ano.is responsible for 90% of fistula-in-ano.
Anorectal abscesses, represent theAnorectal abscesses, represent the
acute presentation of cryptoglandular disease, whileacute presentation of cryptoglandular disease, while
fistulae are the chronic evolution of the samefistulae are the chronic evolution of the same
Other less common causes of fistulae areOther less common causes of fistulae are
CrohnCrohn’’s disease, trauma, anal fissures,s disease, trauma, anal fissures,
carcinoma, radiation therapy, tuberculosis, andcarcinoma, radiation therapy, tuberculosis, and
chlamydial infections.chlamydial infections.
Differential Diagnosis of Fistula-in-ano
Inflammatory bowel disease
Adenocarcinoma of the
Squamous cell carcinoma of
Pelvic inflammatory disease
Anorectal abscesses arise from obstruction of
the anal glands and ducts,
which communicate with the anal crypts located at
the dentate line.
The resulting infection begins in the space
between the internal and external sphincters and
can spread through the perianal spaces, forming
pockets of purulent material.
Locations of anorectal abscesses include (in order
of frequency) (1) perianal, (2) ischioanal,
(3) intersphincteric, (4) supralevator
The location and course of theThe location and course of the
fistula typically reflects the locationfistula typically reflects the location
of the original abscess:of the original abscess:
(1) intersphincteric(1) intersphincteric
(2) transsphincteric(2) transsphincteric
(3) suprasphincteric(3) suprasphincteric
fistulae are classified as either simple or
Simple fistulae are considered to be
intersphincteric or low transsphincteric
)>30%sphincter compromise). Fistulotomy is the
best treatment for this kind of fistula, and is not
expected to put a patient’s continence at risk.
Complex fistulae involve more than 30% of the
sphincter and usually are transsphincteric,
suprasphincteric, or extrasphincteric.
History of an abscess that was eitherHistory of an abscess that was either
drained spontaneously or surgically.drained spontaneously or surgically.
Intermittent or continuous discharge. If itIntermittent or continuous discharge. If it
is intermittent, the patient may haveis intermittent, the patient may have
increased pain and pressure prior toincreased pain and pressure prior to
recurrent drainage, which gives relief.recurrent drainage, which gives relief.
Other symptoms include bleeding,Other symptoms include bleeding,
soreness, pruritis or perianal dermatitis.soreness, pruritis or perianal dermatitis.
Physical ExaminationPhysical Examination
The external opening can be seen as anThe external opening can be seen as an
elevation of granulation tissue dischargingelevation of granulation tissue discharging
pus. (This may be elicited on the digitalpus. (This may be elicited on the digital
rectal examination) Scar from earlierrectal examination) Scar from earlier
procedures mayprocedures may
be appreciated as well as chronic skinbe appreciated as well as chronic skin
changes such as thickened and rednesschanges such as thickened and redness
from persistentfrom persistent
Digital rectal examination may reveal anDigital rectal examination may reveal an
indurated cord-like structure beneath the skin inindurated cord-like structure beneath the skin in
direction of the internal opening.direction of the internal opening.
Inability to palpate the fistula tract implies aInability to palpate the fistula tract implies a
deeper coursedeeper course
and therefore higher transsphincteric fistula.and therefore higher transsphincteric fistula.
Internal openings may be felt as induratedInternal openings may be felt as indurated
or pits that correspond to enlarged papilla, leadingor pits that correspond to enlarged papilla, leading
to a thickened tract.to a thickened tract.
This examination allows visualization of theThis examination allows visualization of the
dentate line for possible identification of internaldentate line for possible identification of internal
openings before surgery, as well as identification ofopenings before surgery, as well as identification of
other pathology such as Crohnother pathology such as Crohn’’s disease ors disease or
GoodsallGoodsall’’s rule, which states that externals rule, which states that external
openings located posteriorly to the coronal lineopenings located posteriorly to the coronal line
are associated with tracts that curve to theare associated with tracts that curve to the
posterior midline before entering the anal canal.posterior midline before entering the anal canal.
external openings anterior to the coronal lineexternal openings anterior to the coronal line
track straight toward the internal opening of thetrack straight toward the internal opening of the
anal canal.anal canal.
Radiological EvaluationRadiological Evaluation
Radiology has a limited role in theRadiology has a limited role in the
evaluation of anal fistulaeevaluation of anal fistulae..
Most cases can be diagnosedMost cases can be diagnosed
and treated based on clinicaland treated based on clinical
Radiological examinations are usefulRadiological examinations are useful
in atypical cases or after reccurencesin atypical cases or after reccurences
Fistulography involves cannulation of theFistulography involves cannulation of the
external opening with injection of waterexternal opening with injection of water
soluble contrastsoluble contrast
It may be useful for evaluation of recurrentIt may be useful for evaluation of recurrent
or complex fistulae.or complex fistulae.
Its use has been generally discouragedIts use has been generally discouraged
because of risk of septicemia in a smallbecause of risk of septicemia in a small
amount of patients and poor visualization ofamount of patients and poor visualization of
anatomic landmarks.anatomic landmarks.
This study has been substituted by otherThis study has been substituted by other
diagnostic modalitiesdiagnostic modalities
CT ScanCT Scan
CT scan has a minor role in theCT scan has a minor role in the
assessment of anal fistulae.assessment of anal fistulae.
The main use of CT scan is toThe main use of CT scan is to
distinguish an abscess requiring drainagedistinguish an abscess requiring drainage
from perirectal cellulites.from perirectal cellulites.
It is done with intravenous and rectalIt is done with intravenous and rectal
It may be useful if MRI is not available orIt may be useful if MRI is not available or
Endoanal UltrasoundEndoanal Ultrasound
The role of ultrasound is toThe role of ultrasound is to::
11--Identify the fistula tract in relation to the internalIdentify the fistula tract in relation to the internal
and external sphinctersand external sphincters
22--To determine if the fistula is simple or complex 3-To determine if the fistula is simple or complex 3-
Define the location of the internal openingDefine the location of the internal opening
The injection of hydrogen peroxide into the fistulaThe injection of hydrogen peroxide into the fistula
opening during ultrasound improvesopening during ultrasound improves
identification of fistulae and their internal openingsidentification of fistulae and their internal openings
by making them hyper instead of hypoechoicby making them hyper instead of hypoechoic..
Magnetic Resonance ImageMagnetic Resonance Image
Accurate classification of fistulae with MRI isAccurate classification of fistulae with MRI is
possible in 89% of patients compared to 61%possible in 89% of patients compared to 61%
using 2-D anal ultrasoundusing 2-D anal ultrasound..
Although MRI seems superior to endoanalAlthough MRI seems superior to endoanal
ultrasound in the assessmentultrasound in the assessment
of fistula-in-ano, anal ultrasound tends to be moreof fistula-in-ano, anal ultrasound tends to be more
useful than MRI because it is more widelyuseful than MRI because it is more widely
available, can be performed quickly in the officeavailable, can be performed quickly in the office
setting, and is less expensivesetting, and is less expensive
MRI is therefore best reserved for cases whereMRI is therefore best reserved for cases where
ultrasound has already failed to identify theultrasound has already failed to identify the
fistula and internal openingfistula and internal opening
Locating the fistulous
tract. The probe is
and allowed to
follow the tract until
it exits through the
This will serve as a
guide for either
or seton placement
After gently passing a probe down the tract through the
external opening an incision may be made on the probe
using a scalpel or electrocautery through the perianal skin
and rectal mucosa.
The edges of the tract should be excised completely,
and care should be taken not to undermine the edges
Once open, the fistulous tract should be cleaned with a
curette to remove any granulation tissue.
At the completion of the procedure, light packing tape may
be placed in the fistula tract
Seton PlacementSeton Placement
Cutting setonsCutting setons
will gradually cut through the sphincter muscle via pressurewill gradually cut through the sphincter muscle via pressure
necrosis, with fibrosis behind the seton, preventing sphincternecrosis, with fibrosis behind the seton, preventing sphincter
retraction and incontinenceretraction and incontinence..
A large Ethibond or other braided suture is placed through theA large Ethibond or other braided suture is placed through the
internal and external openings of the fistulous tract and tiedinternal and external openings of the fistulous tract and tied
down onto the sphincter complexdown onto the sphincter complex..
The seton will then beThe seton will then be ““advancedadvanced”” over the course of theover the course of the
next several weeks until the fistulous tract is completelynext several weeks until the fistulous tract is completely
care must be taken to not advance the seton too quicklycare must be taken to not advance the seton too quickly,,
as the patient will experience a tremendous amount of pain asas the patient will experience a tremendous amount of pain as
well as suffer a complication of sphincter divisionwell as suffer a complication of sphincter division..
Draining setonsDraining setons
will keep the fistulous tract open, allowing for abscess drainagewill keep the fistulous tract open, allowing for abscess drainage
and tract maturation, therefore facilitating a future fistulotomy or otherand tract maturation, therefore facilitating a future fistulotomy or other
fistula closure technique. A vessel loop or large Ethibond suture is passedfistula closure technique. A vessel loop or large Ethibond suture is passed
through the internal and external openings of the fistulous tract and tiedthrough the internal and external openings of the fistulous tract and tied
loosely around the sphincter complexloosely around the sphincter complex..
indications for use of a draining seton includeindications for use of a draining seton include::
))11((complex anorectal fistula extensively involving the externalcomplex anorectal fistula extensively involving the external
sphincter, with the goal of staged fistulotomy; (2) complex anorectal fistula insphincter, with the goal of staged fistulotomy; (2) complex anorectal fistula in
the setting of sepsis; (3) anterior high transsphincteric fistula in a femalethe setting of sepsis; (3) anterior high transsphincteric fistula in a female
))44((high transsphincteric fistula in a patient with AIDS; (5) long-term fistulahigh transsphincteric fistula in a patient with AIDS; (5) long-term fistula
treatment in a patient with active IBD; and (6) concern for fistulotomy leadingtreatment in a patient with active IBD; and (6) concern for fistulotomy leading
to fecal incontinenceto fecal incontinence
Draining setonDraining seton
The seton placedThe seton placed
through the externalthrough the external
and internaland internal
openings and tiedopenings and tied
loosely to maintainloosely to maintain
Fibrin GlueFibrin Glue
Fibrin glue may be used as an alternative means of occluding theFibrin glue may be used as an alternative means of occluding the
fistulous tractfistulous tract..
Following digital rectal examination, the fistulous tract is identified andFollowing digital rectal examination, the fistulous tract is identified and
any granulation tissue at the internal or external openings is gentlyany granulation tissue at the internal or external openings is gently
debrided with a curettedebrided with a curette..
Fibrin glue is then gently injected through the external openingFibrin glue is then gently injected through the external opening
until the tract is fulluntil the tract is full..
Success of this technique is variable, with long-term healing reported atSuccess of this technique is variable, with long-term healing reported at
However, it can be used to avoid a large operation in risky patientsHowever, it can be used to avoid a large operation in risky patients
Fibrin glue is an activated mixture of solution containing fibrinogen,Fibrin glue is an activated mixture of solution containing fibrinogen,
factor XIII, fibronectin, and aprotininfactor XIII, fibronectin, and aprotinin
When applied to the fistula tract, the fibrin clot seals the tract andWhen applied to the fistula tract, the fibrin clot seals the tract and
stimulates migration, proliferation, and activation of fibroblastsstimulates migration, proliferation, and activation of fibroblasts..
Anal Fistula PlugAnal Fistula Plug
This fistula plug made from lyophilizedThis fistula plug made from lyophilized
porcine intestinal collagen is designed toporcine intestinal collagen is designed to
occlude the fistula tract from the internalocclude the fistula tract from the internal
to the external openingto the external opening..
The plug provides a scaffold for theThe plug provides a scaffold for the
ingrowth of native tissueingrowth of native tissue..
Advantages of this technique are theAdvantages of this technique are the
mechanical stable configurationmechanical stable configuration,,
Endorectal Advancement FlapsEndorectal Advancement Flaps
Endorectal advancement flaps were firstEndorectal advancement flaps were first
described by Noble 1902described by Noble 1902,,
This treatment modality consists of removalThis treatment modality consists of removal
and patching of the internal openingand patching of the internal opening
with a muscularwith a muscular––mucosal flap of rectal wallmucosal flap of rectal wall..
Island Flap AnoplastyIsland Flap Anoplasty
Dermal island advancement flap (anocutaneousDermal island advancement flap (anocutaneous
advancement flap). Its use in the treatment ofadvancement flap). Its use in the treatment of
fistulae started in the pastfistulae started in the past
decade, basically to avoid incontinence and mucosaldecade, basically to avoid incontinence and mucosal
ectropion after mucosal flap advancementectropion after mucosal flap advancement..
This procedure has been reported forThis procedure has been reported for
complex or recurrent casescomplex or recurrent cases..
There are good results in terms of healing,There are good results in terms of healing,
postoperative complications, pain, andpostoperative complications, pain, and
wound irrigations are recommended
three to four times daily. In order to promote the healing
from the depth of the wound, The wound must be kept clean.
A post-operative antibiotic treatment
Weekly inspection should be carried out by the surgeon.
Silver nitrate may be applied to prevent overgranulation.
Sphincter function must be evaluated soon after surgery,
Bulky laxatives must be given to allow passage of stools
without straining and to reduce pain.
Non-steroidal anti-inflammatory drugs are useful to reduce
Results and Complications
Satisfactory results may be achieved in the treatment of
anal fistula. Results depend on the type of fistula. The
healing time varies from 6 weeks for the low type to
16weeks or more for the complex variety.
Fistula surgery should be reserved for experienced surgeons
order to reduce as much as possible the high incidence
of recurrence and prevent incontinence.
Two main post-operative complications may occur after
treatment of an anal fistula:
recurrence and incontinence
Recurrence of anal fistula in cases of
cryptoglandular origin is essentially due to
failure to remove the correct anal gland.
The internal opening may not be found
and part of the tract may be buried under the
granulation tissue, including the epithelial
A recurrence rate of up to 10% is observed
If a fistula has been adequately treated and still
recurs, the possibility of Crohn’s disease
must be considered.
Partial early post-operative incontinence is frequent
after surgery of any fistulous tract and is the result of
inflammation, tissue deformity and pain
If the sphincter has been divided, the initial
weakness regresses, and continence has proved to be
adequate within 2–3 weeks.
As many as one-third of the patients have some permanent
disturbance in anal continence,
varying from loss of flatus control to severe faecal incontinence.
To prevent incontinence, there must be a sufficient time interval
between the two operative sessions in a two-stage procedure.
Division of the sphincter muscle must be kept to a minimum.
If sphincter division results in persistent incontinence,
sphincter repair must be considered