Perianal abscesses and Fistulae Flashcards

1
Q

Define Perianal abscesses

A

Collection of pus in the perianal region

Submucous | Subcutaneous | Inter-sphincteric | Ischiorectal | Pelvirectal abscess

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2
Q

Define Perianal fistulae

A

Abnormally chronically infected tract communicating between peritoneal skin and either canal or rectum

Types: Superficial | intersphincteric | Trans-sphincteric | Suprasphincteric | Extrasphincteric
Alternative classification: Low anal (below puborectalis) or High anal (at or above puborectalis) and Pelvirectal (inv. Levator ani)

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3
Q

Aetiology of Perianal abscesses and Fistulae

A

Fistula can cause abscesses and abscesses can cause fistulae

Obstruction and stasis of anal crypt glands -> superinfection spreads to perianal tissues

Fistulae may develop once abscess discharges or has been evacuated

Fistulae may be a complication of Crohn’s disease (multiple fistulae -> pepper pot perineum)

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4
Q

Risk factors for Perianal abscesses and Fistulae

A
Crohn's 
Diabetes
Malignancy (rectal carcinoma)
Clogged anal glands and anal abscess
Radiation
Trauma
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5
Q

Symptoms of Perianal abscesses and Fistulae

A

Constant throbbing pain in perineum (around anus) NOT related to defecation

Fistulae with intermittent discharge (mucous of blood-stained) near the anal region, may be foul smelling

Systemic: fever and chills

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6
Q

Signs of Perianal abscesses and Fistulae on examination

A

Localised tender perianal swelling
Small skin opening with discharge near the anus (open fistula)

DRE: area of induration corresponding to abscess or fistula tract

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7
Q

What is Goodsall’s rule

A

rule of thumb to correlate location internal fistula opening based on location of external fistula opening

* If external opening is anterior to anal canal, the fistula runs radially and directly into the anal canal
* If external opening is posterior to anal canal, fistula tract follows curved path, opening internally in posterior midline
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8
Q

Investigations for Perianal abscesses and Fistulae

A

Clinical diagnosis

FBC/CRP/ESR/Blood cultures: check for infection

MRI: internal pelvic abscesses seen
USS: Can be used to visualise abscesses if DRE is tool painful

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9
Q

Management for Perianal abscesses and Fistulae

A

Surgery ± antibiotics

Abscess incision and drainage (most common)
Hydrogen peroxide or methylene blue injection
Fistulotomy
Seton
Advancement flap
Xenograft (fistula plug)
Fibrin glue

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10
Q

Complications of Perianal abscesses and Fistulae

A

Recurrence (high rate without complete excision)
Sepsis if untreated
Incontinence due to surgery

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