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
what type of fistula is this?
intersphincteric
- 20-45%
- does not penetrate the external sphincter
- extends along the intersphincteric space
what type of fistula is this?
suprasphincteric
- ~20% of cases but likely much less
- track is over the top of the puborectalis (anorectal ring), then downward again through the levator plate to the ischiorectal fossa, and fi nally the skin
- it is anatomically in the supralevator space
- Abscess formation in this space can result in a horseshoe extension around the rectum
which type of fistula has a tendency to develop into horseshoe abscess?
suprasphincteric fistula because the track goes up to the supralevator space before coming down. there it can extend around the rectum and form a horseshoe
what type of fistula is this?
extrasphincteric
- only 2-5%
- passes from skin to ischiorectal fat to levator muscles into the rectum
- it is completely outside of the external sphincters
- What is Goodsall’s rule?
- for what side is Goodsall’s rule more accurate? anterior or posterior?
- posterior fistulas tend to all merge at midline
- anterior fistulas tend to go straight line from opening to inside
Goodsall’s rule is more accurate for posterior ones. 216 pts. 90% of the posterior fistulas drain to midline.
what is the sensitivity and specificity of endorectal ultrasound for anal fistulas?
sensitivity: 87%
specificity: 43%
what are the 4 goals of any anal fistula surgery?
- control the infection/source of sepsis
- closure of the fistula track
- maintain continence
- minimize recurrence
when you do a lay open fistulotomy, the rate of incontinence is highest for what type of fistula? lowest?
lowest: intersphincteric (37%)
highest: extrasphincteric (83%)
what are the indictions for seton?
when a simple fistulotomy is not adviased
- complex fistula
- Crohn’s disease
- if fistulotomy would result in complete incontinence
- rate of recurrence for cutting seton
- rate of fecal incontinence for cutting seton when the internal sphincter was not divided vs. when it was
- as the internal opening goes more proximal, does incontinence rate get better or worse?
- 3-5%
- 5.6% incontinence rate when internal sphincter not divided. 25% when internal sphincter divided
- the higher the internal opening, higher the incontinence rate
What’s one treatment option for high transsphincteric or suprasphincteric fistula?
describe this procedure
Endorectal Advancement Flap (ERAF)
- prone jackknife, lone star
- identify the internal opening and excise the crypt-bearing tissue
- small rim of the anoderm below the internal opening is excised (create a neo-dentate line)
- close the defect with vicryl (2-0)
- make a flap in the submucosal plane. 4-6cm proximally
- curette the fistula tract and close the defect
does using fibrin glue to the tract during advancement flap help with outcome
the use of fibrin glue during ERAF actually is associated with worse outcome compared to just flap alone
full thickness falp vs. partial thickness flap. which one is better?
full thickness flap has a better recurrence rate (5%) compared to partial thickness (35%)
how do the recurrence rates compare in obese vs. non-obese patients?
obese recurrence rate: 28%
non-obese recurrence rate: 14%
- What is LIFT procedure?
- LIFT procedure is appropriate for what kind of fistulas?
- Ligation of Intersphincteric Fistula Tract
- all patients with high transsphinceric fistula
describe the LIFT procedure
- identify the internal opening. can use ureteral stent to stent the fistula tract
- 3-4cm curvilinear incision at the intersphincteric plane
- identify the intersphincteric tract and dissect around the fistula tract being careful not to injure or disrupt the tract. get around it with a right angle
- Doubly suture ligate the tract close to the internal and external sphincter with 2-0 Vicryl and transect it between the sutures
- Inject the external opening to confirm that the tract was divided completely
- Curette the external portion of the fi stula tract
- drain the external opening
- close the incision
what is the fistula closure rate after LIFT procedure?
~75-80%
What constitutes the fibrin glue?
what’s the success rate like? benefit?
- fibrinogen concentrate
- thrombin
- factor XIII (to stabilize the fibrin monomers)
- aprotinin (to preven fibrinolysis)
success rate is anywhere from 10-78% no incontinence is a benefit. not really a first line rx
