Lecture notes for medical students

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7. See notes for bibliography.

2. Format

3. Format
1. Introduction & History
2. Relevant Anatomy, Physiology
3. Aetiology
4. Pathophysiology
5. Pathology
6. Classification
7. Clinical Features
8. Investigations
9. Management
10.Prevention

4. Fistula in Ano

5. Fistula in Ano
• Fistula is an abnormal communication
between two epithelized surfaces.
• A fistula-in-ano is an abnormal tract or
cavity with an external opening in the
perianal area that is communicating with the
rectum or anal canal by an identifiable
internal opening.

6. Anatomy

7. Anatomy
• Hollow tract or cavity.
• Primary opening inside the anal canal.
• Secondary opening in the perianal skin.
• secondary tracts may be multiple and can
extend from the same primary opening.
• Tract lined with granulation tissue.

8. Etiology and Pathophysiology

9. Etiology and Pathophysiology
• Most fistulas are thought to arise as a result
of cryptoglandular infection with resultant
perirectal abscess.
• there are eight to 10 anal crypt glands at the
level of the dentate line in the anal canal,
arranged circumferentially.
• These glands penetrate the internal
sphincter and end in the intersphincteric
plane.

10. Etiology and Pathophysiology
• The cryptoglandular hypothesis states that
an infection begins in the anal canal glands
and progresses into the muscular wall of the
anal sphincters to cause an anorectal
abscess.
• The abscess represents the acute
inflammatory event, whereas the fistula is
representative of the chronic process.

11. Etiology and Pathophysiology
• After surgical or spontaneous drainage in
the perianal skin, a granulation tissue–lined
tract is occasionally left behind, causing
recurrent symptoms.

12. Etiology
Other fistulas develop secondary to-
• trauma (eg, rectal foreign bodies),
• Crohn disease,
• anal fissures,
• Carcinoma
• radiation therapy
• Actinomycoses
• Tuberculosis
• lymphogranuloma venereum

13. Clinical Features

14. Clinical Features
• Demography
• Symptoms
• Signs
• Prognosis
• Complications

15. Demography

16. Demography
• The incidence of a fistula-in-ano
developing from an anal abscess ranges
from 26% to 38%
• prevalence of fistula-in-ano is 8.6 cases per
100,000 population.
• The mean patient age is 38.3 years.
• The male-to-female ratio is 1.8:1.

17. History
Important points-
• Inflammatory bowel disease
• Diverticulitis
• Previous radiation therapy for prostate or
rectal cancer
• Tuberculosis
• Steroid therapy
• HIV infection

18. History
• A review of other systems
• Abdominal pain
• Weight loss
• Change in bowel habits

19. Symptoms

20. Symptoms
• Symptoms generally affect quality of life
significantly,
• Range from minor discomfort and drainage
with resultant hygienic problems to sepsis.
• history of previous pain, swelling, and
spontaneous or planned surgical drainage of
an anorectal abscess.

21. Symptoms
• Perianal discharge
• Pain
• Swelling
• Bleeding
• Diarrhea
• Skin excoriation
• External opening

22. Signs

23. Signs
• Physical findings are the mainstay of
diagnosis.
• external opening
– open sinus
– elevation of granulation tissue.
– Spontaneous discharge of pus or blood via the
external opening may be apparent or
expressible on digital rectal examination.

24. Digital rectal examination (DRE)

25. Digital rectal examination (DRE)
• fibrous tract or cord beneath the skin.
• It also helps to delineate any further acute
inflammation that is not yet drained.
• Lateral or posterior induration suggests
deep postanal or ischiorectal extension.

26. Goodsall Rule

27. Goodsall Rule
• In simple cases, the Goodsall rule can help
to anticipate the anatomy of a fistula-in-ano.
The rule states that fistulas with an external
opening anterior to a plane passing
transversely through the center of the anus
will follow a straight radial course to the
dentate line

28. Goodsall Rule
• . Fistulas with their openings posterior to
this line will follow a curved course to the
posterior midline (see image below).
Exceptions to this rule are external openings
more than 3cm from the anal verge. These
almost always originate as a primary or
secondary tract from the posterior midline,
consistent with a previous horseshoe
abscess

29. Goodsal Rule

30. Classification

31. Classification
Parks Classification –
• intersphincteric,
• transsphincteric,
• suprasphincteric,
• extrasphincteric.

32. Classification

33. Intersphincteric fistula-in-ano
• Result of a perianal abscess
• Common course - It begins at the dentate
line, then tracks via the internal sphincter to
the intersphincteric space between the
internal and external anal sphincters, and
finally terminates in the perianal skin or
perineum
• Incidence - 70% of all anal fistulas
• Other possible tracts - No perineal opening;
high blind tract; high tract to lower rectum
or pelvis

34. Transsphincteric fistula-in-ano
• results from an ischiorectal fossa abscess
• Common course - It tracks from the internal
opening at the dentate line via the internal
and external anal sphincters into the
ischiorectal fossa and then terminates in the
perianal skin or perineum
• Incidence - 25% of all anal fistulas
• Other possible tracts - High tract with
perineal opening; high blind tract

35. Suprasphincteric fistula-in-ano
• Arises from a supralevator abscess
• Course - internal opening at the dentate line
to the intersphincteric space, tracks
superiorly to above the puborectalis, and
then curves downward lateral to the external
anal sphincter into the ischiorectal fossa and
finally to the perianal skin or perineum
• Incidence - 5% percent of all anal fistulas
• Other possible tracts - High blind tract (ie,
palpable through rectal wall above dentate
line)

36. Extrasphincteric fistula-in-ano
• May arise from foreign body penetration of
the rectum with drainage through the
levators,
• Penetrating injury to the perineum
• Crohn disease
• Carcinoma or its treatment
• Pelvic inflammatory disease

37. Extrasphincteric fistula-in-ano
• Common course - It runs from the perianal
skin via the ischiorectal fossa, tracking
upward and through the levator ani muscles
to the rectal wall, completely outside the
sphincter mechanism, with or without a
connection to the dentate line
• Incidence - 1% of all anal fistulas

38. Current procedural terminology
coding
• Subcutaneous
• Submuscular (intersphincteric, low
transsphincteric)
• Complex, recurrent (high transsphincteric,
suprasphincteric and extrasphincteric,
multiple tracts, recurrent)
• Second stage

39. Dfferential

40. Dfferential
• Hidradenitis suppurativa
• Infected inclusion cysts
• Pilonidal disease
• Bartholin gland abscess in females

41. Investigations
• Laboratory Studies
– Routine
– Special
• Imaging Studies
• Tissue diagnosis
– Cytology
• FNAC
– Histology

42. Diagnostic Studies

43. Diagnostic Studies
Imaging Studies
• X-Ray
• USG
• CT
• Angiography
• MRI
• Endoscopy
• Nuclear scan

44. Diagnostic Studies
• Fistulography
• Endoanal Sonography
• MRI
• CT
• Barium meal /Enema
• Anal Manometry

45. Anal Manometry
•

46. Anal Manometry
• Patients in whom decreased tone is
observed during preoperative evaluation
• Patients with a history of previous
fistulotomy
• Patients with a history of obstetrical trauma
• Patients with a high transsphincteric or
suprasphincteric fistula (if known)
• Very elderly patients
•

47. Diagnostic Studies

48. Diagnostic Studies
• Examination under anesthesia
– Examination of the perineum,
– digital rectal examination (DRE),
– Anoscopy
• Proctosigmoidoscopy/colonoscopy

49. Treatment
• No definitive medical therapy
• long-term antibiotic prophylaxis and
infliximab may have a role in recurrent
fistulas in patients with Crohn disease.

50. Treatment
• .

51. Treatment
• Surgery is the treatment of choice
• Goals-
– draining infection
– eradicating the fistulous tract
– avoiding persistent or recurrent disease
– preserving anal sphincter function

52. Operative Therapy
• Fistulotomy
• Seton Placement
• Mucosal Advancement Flap
• Plugs and Adhesives
• Ligation of the intersphincteric fistula tract
(LIFT)
• VAAFT Video-assisted anal fistula
treatment
• SLOFT –Submmucosal Ligation Of Fistula
Trract.

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