Fistula

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Fistula
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• Definition
• Fistula is an abnormal connection between the
  exterior and a hollow viscus or between two
  hollow viscera.
• Fistula in ano is track, lined by granulation
  tissue, that conects deeply in the anal canal or
  rectum and superficially on the skin around the
  anus.

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• Aetiology
• Inflammatory causes ulcerative colitis, Crohns
  disease etc, tuberculosis
• Neoplastic causes cancer rectum or anal canal
• Incidence
• Common and may be simple or complex
• Classified into high or low depending on whether
  the track passes above or below the anorectal ring

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• Pathophysiology
• Inflammation ulceration penetration of the
  ulcer through all layers of the wall of the
  viscus involvement of the adjacent hollow
  viscus in the ulceration connection
  established. Or the ulceration may involve the
  abdominal wall leading to openint of the hollow
  viscus to the outside.

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Fistula in ano

• Pathophysiology
• Fistula in ano usually starts as a perianal
  abscess
• The abscess bursts open and discharges pus
• A track between the perianal skin and the anal
  canal is established
• The infection and suppuration commonly starts in
  an anal gland (glands found at the dentate line
  of the anal canal) and spreads to the perianal
  region.

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Clinical Features

• Signs and symptoms (in order of prevalence)
• Perianal discharge
• Pain
• Swelling
• Bleeding
• Diarrhea
• Skin excoriation
• External opening

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Clinical features

• purulent discharge and drainage of pus and/or
  stool near the anus,
• Irritation of the outer tissues
• Itching and discomfort.
• Pain occurs when fistulas become blocked and
  abscesses recur.
• Flatus (gas) may also escape from the fistulous
  tract.

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• Investigations
• Digital examination
• Proctoscopy
• Probing under anaesthesia
• radiography X- ray Chest
• Routine investigations like Hb, TC, DC, ESR
• Differential diagnosis
• Ulcerative colitis
• Crohns disease of the anal canal and rectum
• Anal tuberculosis (look for PT)
• Actinomycosis
• Cancer rectum

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• Complications
• Branching of the fistulous track
• Water can perineum

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Treatment

• Ordinary fistulae need laying the track open and
  formation of a groove which will heal from the
  bottom of the groove
• Occasionally a high fistula may need a two stage
  operation I stage of laying open as far as
  possible then inserting a Setons suture II
  stage laying the rest of the tract open

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Evolution of a fistula
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Low fistula in ano
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• A fistula-in-ano is diagnosed when a probe has
  been passed between the opening on the skin's
  surface and the interior opening

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Perirectal abscess
Perirectal Abscess
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Fistula in ano external opening
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Other considerations

• Past medical history
• Important points in the history that may suggest
  a complex fistula include the following
• Inflammatory bowel disease
• Diverticulitis
• Previous radiation therapy for prostate or rectal
  cancer
• Tuberculosis
• Steroid therapy
• HIV infection

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• Parks classification system
• The Parks classification system defines 4 types
  of fistula-in-ano that result from
  cryptoglandular infections.
• Intersphincteric
• Common course - Via internal sphincter to the
  intersphincteric space and then to the perineum
• Seventy percent of all anal fistulae
• Other possible tracts - No perineal opening high
  blind tract high tract to lower rectum or pelvis

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• Transsphincteric
• Common course - Low via internal and external
  sphincters into the ischiorectal fossa and then
  to the perineum
• Twenty-five percent of all anal fistulae
• Other possible tracts - High tract with perineal
  opening high blind tract

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• Suprasphincteric
• Common course - Via intersphincteric space
  superiorly to above puborectalis muscle into
  ischiorectal fossa and then to perineum
• Five percent of all anal fistulae
• Other possible tracts - High blind tract (ie,
  palpable through rectal wall above dentate line)

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• Extrasphincteric
• Common course - From perianal skin through
  levator ani muscles to the rectal wall completely
  outside sphincter mechanism
• One percent of all anal fistulae

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Ischiorectal fossa
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Anorectal musculature frontal section
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• 1.intersphincteric 2.transsphincteric
  3.supralevator

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