Anal Fistula

Question 1

Define “anal fistula”

Answer 1

abn communications, hollow tracts lined w/ granulation tissue connecting the primary opening inside the anal canal to a secondary opening in the perinanal skin. Usually assoc w/ anorectal abscess (obstruction of ducts => infxn)

Question 2

What are some conditions that are associated w/ anal fistulae?

Answer 2

Crohn’s ds
TB
Actinomycosis
Hidradenitis suppurativa

Question 3

Discuss the epidemiology of anal fistulae

Answer 3

commonly affect those in 3rd-5th decade of life

9/100 000 per yr in Western Europe

Question 4

How does a pt w/ an anal fistula present?

Answer 4

intermittent purulent discharge +/- bleeding

pain - increases until temp relief that occurs w/ pus discharge

Question 5

What is Goodsall’s Rule?

Answer 5

For fisula w/in 3cm of anal verge + post to line drawn thru ischial spines if:

• ant to transverse anal line: straight radially directed tract into anal canal
• post to transverse line: curve tract open into anal canal midline post (@ level of dentate line)

Question 6

Which investigations are done for a pt presenting w/ an anal fistula?

Answer 6

Endoanal U/S
MRI
CT/fistulography

Question 7

What is an inter-sphincteric fistula and how do you manage it?

Answer 7

common cause: int sphincter -> intersphincteric space -> perineum. 70% of anal fistulae
other possible tracts: no perineal opening, high blind + high tract to lower rectum/pelvis

mx: fistulotomy

Question 8

What is a trans-sphincteric fistula and how do you manage it?

Answer 8

Common course: low via int & ext sphincters => ischiorectal fossa => perineum. 25% anal fistulae
other possible tracts: high tract w/ perineal opening + high blind tract

mx: Low = fistulotomy; high/ant fistulae in women = cutting seton/partial fistulectomy & endoanal flap/injection of fibrin glue

Question 9

What is a supra-sphincteric fistula and how do you manage it?

Answer 9

common course: via inter-sphincteric space sup to above puborectalis mm into ischiorectal fossa -> perineum. 5%

mx: cutting seton/endorectal advancement flap/sphincter reconstruction

Question 10

What is an extra sphincteric fistula and how is it managed?

Answer 10

common course: perianal skin thru levator ani mm to rectal wall completely outside the sphincter mech. 1%. Not related to sphincter complex, assoc w// Crohn’s, Ca, recurrent fistulas

mx: endorectal advancement flap, laparotomy & resection of involved intestinal segment + curretage of fistula tract