2. Definition:
Is an abnormal hollow tract or cavity
that is lined with granulation tissue and
that connects a primary opening inside
the anal canal to a secondary opening
in the perianal skin.
3. Anatomy:
The external sphincter
muscle:
Is a striated muscle.
Under voluntary control.
Three components:
submucosal, superficial,
and deep muscle.
The internal sphincter
muscle:
Is a smooth muscle.
Under autonomic control.
Is an extension of the
circular muscle of the
rectum.
4.
5. Etiology:
In the vast majority of cases, fistula is caused by a previous
anorectal abscess.
Other fistulas develop secondary to trauma.
Crohn’s disease.
Anal fissures.
Carcinoma.
Radiation therapy.
Actinomycoses, tuberculosis and chlamydial infection.
Fecal material act as foreign body.
6. Pathology:
Infection usually affects anal glands at the level of dentate line.
Spread of infection may occur:
Downward: Perianal abscess and intersphincteric fistula.
Upward: Pelvic abscess and suprasphincteric fistula.
Outward: Ischorectal abscess and trassphinteric fistula.
8. Old Classifications:
Low vs high.
Sub cutaneous.
Sub mucous
Simple vs complex.
With or without extension.
Single or multiple.
9. Goodsall’s rule classification:
This rule states:
* A plane passing transversely through the center of the anus
then:
Fistulas anterior to the
plane:
Will follow a straight
radial course to the
dentate line.
Has its own internal
opening.
Fistulas posterior to the
plane:
Will follow a curved
course to the
posterior midline.
Open by common
internal opening.
10.
11. Parks classification:
is the one most commonly used.
This system defines four types of fistula.
1-Inter-sphincteric 70%.
2-Trans-sphincteric 25%.
3-Supra-sphincteric 5%.
4-Extra-sphincteric 1%.
12. Inter-sphincteric fistula:
Incidence - 70% of all anal fistulas.
It is the result of a perianal abscess.
It begins at the dentate line, then tracks via
the internal sphincter to the intersphincteric
space between the internal and external
anal sphincters, and finally terminates in the
perianal skin or perineum.
13. Trans-sphincteric fistula:
Incidence - 25% of all anal fistulas.
Results from an ischiorectal fossa abscess.
Common course - It tracks from the internal
opening at the dentate line via the internal
and external anal sphincters into the
ischiorectal fossa and then terminates in the
perianal skin or perineum.
14. Supra-sphincteric fistula:
Incidence - 5% percent of all anal fistulas.
It arises from a supralevator abscess.
It passes from the internal opening at the
dentate line to the intersphincteric space, tracks
superiorly to above the puborectalis, and then
curves downward lateral to the external anal
sphincter into the ischiorectal fossa and finally
to the perianal skin or perineum.
15. Extra-sphincteric fistula:
Incidence - 1% of all anal fistulas.
It may arise from foreign body penetration of the
rectum or Crohn disease or carcinoma.
It runs from the perianal skin via the
ischiorectal fossa, tracking upward and
through the levator ani muscles to the rectal
wall, completely outside the sphincter
mechanism, with or without a connection to the
dentate line.
18. History:
History of previous surgical drainage of an anorectal abscess.
Perianal discharge.
Pain.
Swelling.
Bleeding.
Diarrhea.
Skin excoriation.
External opening.
Perianal discharg.
19. Physical Examination:
The examiner should observe the entire perineum,
looking for:
An external opening that appears as an open sinus
or
Elevation of granulation tissue.
Discharge of pus or blood via the external opening
may be apparent.
Digital rectal examination (DRE) may reveal a fibrous
tract or cord beneath the skin.
28. It has to be differentiated from
other causes of anal pain:
Anal fissure.
Thrombosed hemorrhoids.
Levator spasm.
Sexually transmitted diseases.
Proctitis.
Cancer.
29. Treatment :
Fistulotomy.
Fistulectomy.
Seton Placement.
Single-stage seton (cutting).
Two-stage seton (draining/fibrosing).
Mucosal Advancement Flap.
Plugs and Adhesives.
Ligation of the intersphincteric fistula tract (LIFT).
Treatment of the underlying cause.
