Perianal Fistula Flashcards
What is perianal fistula?
Abnormal connection between the anal canal and the perianal skin.
Associated with anorectal abscess formation
Aetiology
Perianal abscess most commonly
IBD
TB, DM, HIV
History of trauma to anal region
Previous radiation therapy
Clinical features
Recurrent perianal abscesses
Intermittent or continuous discharge onto the perineum of mucus, blood, pus or feaces.
Examination findings
External opening on the perineum may be seen
Fully open or covered in granulation tissue
Fibrous tract may be felt underneath the skin on DRE
What can be used to clinically predict the trajectory of a fistula tract?
The Goodsall Rule
Explain the Goodsall Rule
Depends on the location of the external opening.
External opening posterior to the transverse anal line -> Fistula tract wll follow a curved course to the posterior midline
External opening anterior to the transverse anal line -> fistula tract will follow a straight radial course to the dentate line.
Ix
Proctoscopy to visualise the opening of the tract
Complex fistula might need MRI imaging.
Classification system
Park’s classification system
Explain Park’s
Divides anal fistulae into four distinct types:
Intersphincteric fistula (most common)
Trans-sphincteric fistula
Supra-sphincteric fistula (least common)
Extra-sphincteric fistula
What does management depend on?
Cause and site
If the patient has no symptoms a conservative approach may be used.
What are the most common surgical approaches?
Fistulotomy
Placement of a seton
Explain fistulotomy
Most suitable for superifical disease
Invlves laying the tract open by cutting through the skin and subcut tissue
Then allow it to heal by secondary intention
Explain placement of a seton.
More suitable for high tract disease
Trying to bring the fistula together and close the tract.
It is quite common for patients with complex anal fistulas to require several repeat procedures
Difference in complications of low track course vs high.
Faecal incontinence is more common in high tract course fistulae.
