Anal fistula

Question 1

What is an anal fistula?

Answer 1

abnormal collection between the anal canal and perianal skin

Question 2

What can an anal fistula form from?

Answer 2

An abscess

Question 3

What are the risk factors for anal fistulas?

Answer 3

Anal abscess, IBD, TB, diabetes, HIV, trauma to the anus, radiation at the anal region

Question 4

What are the clinical features of an anal fistula?

Answer 4

chronic anal infection, so intermittent or continuous discharge onto the perineum with mucus, blood, pus or faeces, severe pain, swelling, change in bowel habit and systemic infection

Question 5

What can be found on examination of an anal fistula?

Answer 5

external opening on the perineum- fully open or covered in granulation tissue, fibrous tract under the skin on a DRE

Question 6

What is the goodsall rule?

Answer 6

Predicts the trajectory of a fistula tract depending on the location of the external opening

Question 7

When will a fistula tract follow a curved course to the posterior midline according to goodsall rule?

Answer 7

external opening posterior to the transverse anal line

Question 8

When will a fistula tract follow a straight radial course to the dentate line according to goodsall rule?

Answer 8

External opening anterior to the transverse anal line

Question 9

What investigations would you do for an anal fistula?

Answer 9

Rigid sigmoidoscopy can be used to visualise the opening of the tract in the anal canal, can also do fistulogrpahy, endo-anal ultrasound, MRI

Question 10

What are the parks classification systems 4 types of anal fistulae?

Answer 10

Inter-spincteric fistula (most common) trans sphincteric fistula, extra spincteric supra spincteric fistula (least common

Question 11

What is the management for an anal fistula?

Answer 11

Fistulotomy- opens the tact and allows it to heal by secondary intention, a probe is passed into the tract and the skin, sub tissue and internal sphincter and divided in turn opening the tract, or a seton