Ch.14 - Abscess/Fistulas Flashcards
epidemiology of anorectal abscess - male vs. female? - mean age?
- male > female, 3:1
- mean age ~40 (20-60)
What are the borders of the ischiorectal space?
- medial/lateral/superior
- anterior/posterior
- superior/medial: levator, external sphincter
- lateral: obturator internus and its fascia along the ischium
- anterior: transverse perineal muscle
- posterior: gluteus maximus, sacrotuberus ligament
The ischioc rectal fossas on either side are connected to each other by what space?
postanal space
what are the risks of fistula formation depending on the location of the abscess? which location for the abscess has the highest risk for fistula formation?
compared to perianal, ischiorectal has the highest risk. 8 times more.
intersphincteric 3 times more
in normal people perianal abscess you’re trying to cover e.coli, bacteroides, enterococcus. in immunosuppressed pts what else should you be concerned about?
neisseria gonorrhea
chlamydia
CMV
herpes simplex
when should you get wound culture for perianal abscess?
high-risk patients
individuals with recurrent/chronic disease
What’s a Henley procedure? When do you use it?
what’s a modified Henley?
for horseshoe abscess, arising from deep postanal space.
- Open posterior drainage through the anococcygeal ligament
- posterior midline incision of the internal sphincter
- open drainage of the bilateral ischiorectal fossae to control lateral tracks
Modifications:
- limiting drainage to internal sphincterotomy followed by elliptical incisions over bilateral ischiorectal fossae
what kind of fistulas have the best outcome when doing fistulotomy at the time of abscess drainage?
low fistulas, superficial (<30-40% external sphincter involvement)
what is the rate of urinary retention after I&D of perianal abscess?
what about for fistulotomy?
for hemorrhoidectomy?
abscess I&D: 2.3%
fistulotomy: 6.3%
hemorrhoid: 22%
What is the recurrence rate for perianal abscess after I&D? Recurrence of horseshoe abscess after drainage?
4-31%, 13% median 18-50% for horseshoe
For perianal nec fasc there’s no evidence to do diverting colostomy but when would you consider it?
Grossly infected sphincter muscle, and anorectal perforation, or immunocompromised
describe the pathophysiology of anal fistula
- anal crypts get blocked by debris/stool
- infection develops @ the anal glands
- path of least resistence. infection spreads to intersphincteric space
can be a result of trauma, Crohn’s, malignancy, TB
- true incidence of anal fistula following abscess formation is close to what %?
- what if the abscess recurs?
- 30%
- if the abscess recurs, about 40-50% of them are because of fistula in ano
- what’s a complex fistula?
- what % of all fistulas are considered complex?
not standardized but if:
- it’s a high transsphincteric fistula
- or if fistulotomy would result in incontinence
- ALL anterior transsphincteric fistula in women
- any by Crohn’s/malignancy/surgery
- suprasphincteric, extrasphincteric
50% of all fistulas are considered complex
what type of fistula is this?
transsphincteric
- most common. 30-60%
- penetrates the external sphincter below the level of the puborectalis muscle, exiting somewhere in the ischiorectal fossa
- be careful with these to not make a false track while looking for the opening into the rectum