Anorectal Abscess and Fistula

Question 1

Most common etiology of anorectal abscess

Answer 1

Blockage of the anal crypts that leads to infection of the anal glands

Question 2

Frequency of fistula formation from anal abscesses

Answer 2

40-60%

Question 3

Horseshoe abscess anatomy

Answer 3

bilateral ischiorectal fossa abscess originating in the deep postanal space

Question 4

Erythema, palpable swelling, and tenderness are typically seen in what kind of anorectal abscesses?

Answer 4

Perianal or ischiorectal abscesses

Question 5

Fullness on DRE in th eposterior anal canal indicates what type of abscess?

Answer 5

Deep postanal space abscess

Question 6

Exquisite tenderness on DRE without external signs usually indicates what kind of abscess?

Answer 6

Intersphincteric abscess

Question 7

Sepsis with few physical finding may indicate what type of abscess?

Answer 7

Supralevator abscess

Question 8

Treatment for intersphincteric abscesses

Answer 8

Unroofing

Question 9

Treatment for large ischiorectal abscesses

Answer 9

Multiple counter incisions and penrose pacement between incisions to allow drainage

Question 10

Treatment for hemi/horseshoe abscesses

Answer 10

Radial incision in posterior midline between anus and coccyx with external sphincter and anococcygeal ligament spread in the midline.
Drain the responsible anal gland by dividing the distal internal sphincter in the posterior midline.
Make counter incisions laterally and connected to deep postanal space and penrose drains placed.
Seton placement if fistula is present.

Question 11

Intersphincteric fistula anatomy

Answer 11

Involve only part of internal anal sphincter muscle

Question 12

Transsphincteric fistula anatomy

Answer 12

Involve varying amounts of both internal and external anal sphincter muscles

Question 13

Low transsphincteric fistula anatomy

Answer 13

Involves the internal and distal 1/3 of the external anal sphincter muscles

Question 14

High transsphincteric fistula anatomy

Answer 14

Involves the internal and more than half the external anal sphincter muscles

Question 15

Suprasphincteric fistula anatomy

Answer 15

Involves the entire external anal sphincter muscle

Question 16

Extrasphincteric fistula anatomy

Answer 16

Do not involve the anal sphincters- typically not cryptoglandular in origin

Question 17

Goodsall’s Rule

Answer 17

Posterior external fistula openings have a curved track and an internal opening in the posterior midline
Anterior external fistula openings have a straight radial track the the internal opening, EXCEPT when they are >3cm from the anal verge, in which case they have a curved track opening in the internal posterior midline.