Chapter 48: Anus- Fistula in Ano

Question 1

What is it?

Answer 1

Anal fistula, from rectum to perianal skin

Question 2

What are the causes?

Answer 2

Usually anal crypt/gland infection (usually perianal abscess)

Question 3

What are the signs/symptoms?

Answer 3

• Perianal drainage
• perirectal abscess
• recurrent perirectal abscess
• diaper rash
• itching

Question 4

What disease should be considered with fistula in ano?

Answer 4

Crohn’s disease

Question 5

How is the diagnosis made?

Answer 5

Exam, proctoscope

Question 6

What is Goodsall’s rule?

Answer 6

Fistulas originating anterior to a transverse line through the anus will course straight ahead and exit anteriorly, whereas those exiting posteriorly have a curved tract

Question 7

What is the management of anorectal fistulas?

Answer 7

1. Define the anatomy
2. Marsupialization of fistula tract (i.e., fillet tract open)3
3. Wound care:
   
   1. routine sitz baths
   2. dressing changes
4. Seton placement if fistula is through the sphincter muscle

Question 8

What is a seton?

Answer 8

• Thick suture placed through fistula tract to allow slow transection of sphincter muscle
• scar tissue formed will hold the sphincter muscle in place and allow for continence after transection

Question 9

What percentage of patients with a perirectal abscess develop a fistula in ano after drainage?

Answer 9

≈50%

Question 10

How do you find the internal rectal opening of an anorectal fistula in the O.R.?

Answer 10

Inject H2O2 (or methylene blue) in external opening—then look for bubbles (or blue dye) coming out of internal opening!

Question 11

What is a sitz bath?

Answer 11

Sitting in a warm bath (usually done after bowel movement and TID)