Fistula in ano

Question 1

What are the main causes for fistula in ano?

Answer 1

1) Infected anal gland
2) Crohns disease
3) Radiation proctitis
4) Foreign body
5) Obstetric emergency
6) Infection - TB, AIDs, actimycosis (immunocompromised), Chlamydia (can cause lymphgranuloma vereneum)
7) Malignancy

Question 2

What is the typical presentation for fistula in ano?

Answer 2

“non healing” perianal abscess
Chronic purulent drainage
Pustule like lesion perianal region
Intermittent rectal pain with defecation

Question 3

Describe the tract for a intersphinteric fistula.

Answer 3

Starts at the dentate line, passes between the internal and external sphincter, and ends at anal verge

Question 4

Describe the tract for a transphinteric fistula.

Answer 4

Starts at dentate line, passes through internal and external anal sphincter to ischiorectal fossa, and ends in skin overlying buttocks.

Question 5

Describe the tract for a suprasphinteric fistula.

Answer 5

Starts in the anal crypt, encircles the entire sphincter apparatus, into the perirectal space, and terminates in the intersphinteric fossa.

Question 6

Describe the tract for a extrasphincteric fistula.

Answer 6

This is usually very high in the anal canal, proximal to the dentate line, encompasses the entrie sphincter apparatus and terminates at the skin of the buttocks.

These do not typically originate from anal crypt but rather trauma, rectal foreign bodies, crohn disease, iatrogenic injury.

Question 7

What are the forms of classification for fistula in ano?

Answer 7

Parks/Gordon/Hardcastle

• intersphincteric, transphinteric, suprasphinteric, extrasphinteric, superficial

Complexity

• Complex -> transphinteric fistulas > 30% external sphincter, suprasphincteric, extrasphincteric, horseshoe, or associated with crohn’s, radiation, faecal incontinence, malignancy
• Simple -> < 30% of external anal sphincter

Question 8

What is the main goal of surgical therapy?

Answer 8

Eradicate fistual while maintaing faecal continence

Question 9

What is goodsall’s law?

Answer 9

1) all fistula tracks with external opening posterior to a line drawn between the ischial spines travel in a curvilinear fashion to the posterior midline.
2) All tracts anterior to this line enter the anal canal in a radial fashion.