Anal Fistula

Question 1

What is a fistula

Answer 1

An abnormal connection from one epithelial surface to another

Question 2

What is a perianal fistula

Answer 2

abnormal connection between the anal canal and the perianal skin

Question 3

What are the majority of the perianal fistulas associated with

Answer 3

anorectal abscesses

Question 4

What are the causes of perianal fistulas

Answer 4

Due to perianal abscesses ( over90%)

IBD both UC and crohns

Systemic diseases - TB, diabetes, HIV

History of trauma - in the anal region.

Previous radiation to the anal region

Question 5

How do perianal fistula present

Answer 5

1. recurrent perianal abcesse

2. discharge onto the perineum, including mucus, blood, pus, or faeces.

Question 6

What is the goodsall rule

Answer 6

used clinically to predict the trajectory of a fistula tract, depending on the location of the external opening:

Question 7

According to the goodsall rule What is the trajectory of the fistula that is anterior to the transverse anal line

Answer 7

fistula tract will follow a straight radial course to the dentate line

Question 8

According to the goodsall rule What is the trajectory of the fistula that is posterior to the transverse anal line

Answer 8

fistula tract will follow a curved course to the posterior midline

Question 9

What investigation is used to investigate anal fistulas

Answer 9

Proctoscopy can be used to visualise the opening of the fistula in the anal canal

Question 10

What is parks classification

Answer 10

Helps to divide fistulas into 4 distinct types

Question 11

What are the four types of fistulas according to parks classification

Answer 11

Inter-sphincteric fistula ( most common )

Trans-sphincteric fistula

Supra-sphincteric fistula ( least common )

Extra-sphincteric fistula

Question 12

What is the treatment of asymptomatic anal fistulas

Answer 12

Conservative treatment

Question 13

What are the surgical treatments available

Answer 13

1. fistulotomy (suitable for superficial / submucosal fistulae) involves laying the tract open and allowing it to heal by secondary intention.
   A probe is passed along the tract, allowing the the skin and subcutaneous tissue* to be divided in turn, to lay the tract open.
2. placement of a seton (a rubber sling) though the fistula promotes through the tract and the opening of the perianal skin adjacent to the external opening, attempting to bring together and close the fistula, also preventing abscess formation