well known perianal abscess and fistula-in-ano in summary for medical students

1. SUMMARY OF ANORECTAL INFECTIONS
Definition in this summary = anorectal abscess and fistula-in-ano or anal fistula
Anorectal abscess = acute condition
Fistula-in-ano = chronic condition
Fistulous abscess = simultaneous
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Pathogenesis:
Anal gland (at crypt) obstruction  stasis  infection
For fistula-in-ano: infection  epithelialization to fistula
Predominant organisms: Mixed:
E.coli (22%),
Enterococcus spp. (16%),
Bacterioides fragilis (20%)
History taking: pain, swelling, diarrhea
Physical examination:
- Look around buttock and anus
- PR if not severe pain or no lesion
- Proctoscopy and sigmoidoscopy in fistula-in-ano
(anorectal abscess is painful so no proctoscope)
Investigations: mostly done in diificult FIA and recurrence
 fistulograpy, endoanal US, MRI, BE, colonoscope
Conditions that antibiotics have the role:
Extensive cellulitis
Systemic signs of infection (sepsis)
Immunocompromised host: DM, valvular heart
disease, HIV
Atypical microbes: TB, actinomycosis

2. SUMMARY OF ANORECTAL INFECTIONS
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Content Anorecal abscess Fistula-in-ano
History taking Pain with swelling, Predisposing diarrhea, Bleeding per
rectum
Discharge, Pain (34%), Swelling, Bleeding, Diarrhea
Physical exam Redness, Heat, Swelling (not in intersphincteric abscess),
pain, Loss of function, Mass when PR (mostly impossible
to PR), Pus exuding, Inguinal LN enlargement
External opening: granulation
Purulent serosanguinous discharge when compression
Goodsall’s rule:
• Opening posterior to coronal plane: fistula originates
from dorsal midline
• Opening anterior: runs directly to nearest crypt
example

3. SUMMARY OF ANORECTAL INFECTIONS
Content Anorectal abscess Fistula-in-ano
classification
In supralevator abscess: determine to origin  ischioanal,
intersphincteric, or pelvic (diverticulitis, appendicitis, Crohn’s disease
A – intersphincteric B – treansphincteric
C – suprasphicteric D – extrasphincteric
treatment Adequately drain: cruciate incision closed to anal verge
Incision via intersphincteric groove in interphincteric abscess
Supralevator: drainage via origin  rectal lumen, ischioanal fossa,
abdominal wall
Horseshoe abscess: Hanley’s or modified Hanley’s
Fistulotomy – used in simple interphincteric and low transphincteric
Fistulectomy – higher incontinence than fistulotomy
LIFT – used in high transphincteric
Seton – complex fistula, high trans and suprasphincteric
Endorectal advancement flap -