Fistula in ano

Dr. Shamim Khan
HMO, Surgery Unit – 1, Ward - 24

 A fistula-in-ano, or anal fistula, is a chronic
abnormal communication, usually lined to
some degree by granulation tissue, which runs
outwards from the anorectal lumen (the
internal opening) to an external opening on the
skin of the perineum or buttock.

Ref: Bailey & Love’s Short Practice of Surgery
25th edition.

A doctor and a patient
with fistula in ano. Sketch from a
15th-century Flemish copy of Jan
Yperman's Cyrurgie.

External opening of
a fistula-in-ano

 Nearly always caused by previous perianal
abscess formation
 Crohn's disease
 Diabetes Mellitus
 Tuberculosis
 Lymphogranuloma venerum
 Actinomycosis
 Rectal duplication
 Trauma
 Radiotherapy
 patients who are immunocompromised for
any reason (HIV infection, malignancy)

A fistula-in-ano complicates 30-50% of perianal abscesses.

Park’s Classification
(according to the relationship of primary tract to the anal sphincters)

 Intersphincteric (45%)
 Simple low tract
 High tract
 High tract with rectal opening
 Extra rectal extention
 Trans-sphincteric (40%)
 Uncomplicated
 High tract
 Suprasphincteric
 Uncomplicated
 High tract
 Extrasphincteric
 Secondary to trauma
 Secondary to anorectal disease
 Secondary to pelvic inflammation

Ref: The ASCRS textbook of colon and rectal surgery
By Bruce G. Wolff, James W. Fleshman, David E. Beck

Based on level of internal opening related to anal sphincters

 Low variety

 High variety
If the internal opening
begins above the anal
sphincter then the fistula
is described as 'high'.
Usually rare.

 Intermittent discharge
(purulent or bloody)

 Pain
(which increases until temporary
relief occurs when pus discharges)

 Pruritis ani

 Perviousepisode of
anorectal sepsis

 History : Full medical history including
obstetric, gastrointestinal, anal surgical and
continence are necessary.

Before any surgical procedure is carried out
an EUA should be performed.

 EUA: A full examination/inspection of the perineum
followed by DRE & Proctosigmoidoscopy.
 DRE examination - area of induration, fibrous tract and
internal opening may be felt.
 Proctosigmoidoscopic inspection - to evaluate the
rectal mucosa for any underlying disease process.

 Site of internal opening.
 Site of external opening.
 The course of primary tract
 Presence of secondary extention.
 Sphincter strength.
 The presence of other condition complicating
the fistula.

 If the external opening
is anterior to the line,
the fistula usually runs
directly into the anal
canal.

 If the external opening
is posterior to the line,
the fistula usually curves
to the posterior midline
of the anal canal.

 Fistulography

 Endoanal ultrasound

 MRI

 Reveal primary
and secondary
tract.
 Useful if an
extrasphincteric
fistula suspected

 Determine sphincter
integrity
 Complexity of the
fistula

Horse shoe fistula

Considered „gold standard‟ for fistula-in-ano imaging

High variety supra-sphicteric fistula Horse shoe fistula

 Fistulotomy (The laying open technique)
 Fistulectomy
 Setons
 Fibrin Glue Sphincter preserving techniques
 Anal fistula plug
 Advancement Flap

 It involves division of
all structures lying
between internal and
external openings.

 Applied mainly to low
variety
intersphincteric and
trans-sphinceric
fistula

 The traditional fistulotomy surgery usually
results in large and deep wounds which can
take months to heal.
 “High” often indicates – high risk of faecal
incontinence if laid open.
 Sphincter preserving techniques are
preferable than laid open techniques.

 Preferable surgical option for high variety.
 Setons are usually made from rubber slings
 2 types of seton suture can be placed

 Draining Seton
 Facilitates draining of sepsis
 Left loose and allows fistula to heal by fibrosis
 Cutting Seton
 Slowly "cheese-wires" though the sphincter
muscle
 Allows fibrosis to take place behind as it
gradually cuts through

 The Anal fistula plug is a minimally invasive
and sphincter-preserving alternative to
traditional fistula surgery.
 The plug is a conical device and is placed by
drawing it through the fistula tract and
suturing it in place.
 the plug, once implanted, incorporates
naturally over time into the human tissue
(human cells and tissues will 'grow' into the
plug), thus facilitating the closure of the
fistula.

As with most anorectal disorders, follow-up
care includes:
 Perianal baths,
 analgesics for pain,
 stool bulking agents, and
 good perianal hygiene.

Fistula in ano

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