anorectal abscess and fistula-in-ano in depth from general surgical residents. ref: Gordon and Nivatvongse 2007. Good luck!

1. Anorectal Infection:
From Anatomy to Surgical Approach
Facebook: Happy Friday Knight
General Surgical Residency Program
Thailand

2. • Definition
• Relevant anatomy
• Etiology
• Pathogenesis
• Diagnosis
• Anorectal abscess
• Fistula-in-ano

3. • Anorectal infection is this presentation:
anorectal abscess and fistula-in-ano
• Anorectal abscess: acute condition
• Fistula-in-ano: chronic condition
• Fistulous abscess: both conditions considered
simultaneously

4. Relevant Anatomy

5. Relevant Anatomy
• Anal Canal
• Muscles
• spaces

6. Netter’s Atlas of anatomy.
0, 2, 4, 7, 11, 15
0 = anal verge
2 = dentate line
4 = anorectal ring
7 = lower to midrectum =
middle valve of Houston –
anterior peritoneal
reflection
11 = mid to upper rectum
15 = upper rectum to
rectosigmoid junction

7. Anal Canal
• Anatomical anal canal: anal verge to dentate
line
– Between columnar and non-keratinized squamous
epithelium
• Surgical anal canal: anal verge to anal column
(anorectal junction: the point passing through
levator ani)
– 4 cm long
– Surrounded by strong muscles

8. Gordon PH, Nivatvongs S. Principles and practice of surgery for the colon, rectum, and
anus. 3rd ed. New york: Informa healthcare USA, 2007.

9. Surgical Anal Canal
• Columns of Morgagni: pleated appearance
narrowing of rectum into anal canal
– small crypts at lower portion: obstruction causes
infection
• Musculature: 2 tubes
– Inner
• Smooth muscles
• Innervated by autonomic nervous system
– Outer
• Skeletal muscles
• Somatic innervation

10. Lining of Anal Canal
• Dentate line: transitional zone between
colorectal columnar epithelium and non-
keratinized squamous epithelium
– 2 cm from anal verge
• Anal verge: between non-keratinized
(anoderm) and keratinized squamous
epithelium

11. https://histologyblog.com/2014/10/
22/histoquarterly-haemorrhoids/

12. Lining of Anal Canal
• Transitional zone:
– Or cloacogenic zone
– 6-12 mm above dentate line
– Extremely variable histology

13. Anorectal Muscles
• Internal sphincter
• Conjoined longitudinal
• External sphincter
• Perineal body
• Pelvic floor: levator ani and coccygeus
• Anorectal ring

14. Netter FH. Atlas of human anatomy. Philadelphia: Elsevier, 2009.

15. Netter FH. Atlas of human anatomy. Philadelphia: Elsevier, 2009.

16. Gordon PH, Nivatvongs S. Principles and practice of surgery for the colon, rectum, and
anus. 3rd ed. New york: Informa healthcare USA, 2007.

17. Anorectal Spaces
• Perianal
• Ischioanal
• Intersphincteric
• Supralevator
• Submucous
• Superficial postanal
• Deep postanal
• retrorectal

18. Gordon PH, Nivatvongs S. Principles and practice of surgery for the colon, rectum, and
anus. 3rd ed. New york: Informa healthcare USA, 2007.

19. Gordon PH, Nivatvongs S. Principles and practice of surgery for the colon, rectum, and
anus. 3rd ed. New york: Informa healthcare USA, 2007.

20. Gordon PH, Nivatvongs S. Principles and practice of surgery for the colon, rectum, and
anus. 3rd ed. New york: Informa healthcare USA, 2007.

21. Etiology
• Nonspecific: cryptoglandular infection
• Specific:
– CD
– UC
– TB
– Actinomycosis
– Foreign body
– Carcinoma, lymphoma, leukemia
– Pelvic inflammation
– Trauma
– radiation

22. Pathogenesis
• Anal gland (at crypt) obstruction  stasis 
infection
• For fistula-in-ano: infection  epithelialization
to fistula

23. Gordon PH, Nivatvongs S. Principles and practice of surgery for the colon, rectum, and
anus. 3rd ed. New york: Informa healthcare USA, 2007.

24. • Predominant organisms: Mixed:
– E.coli (22%),
– Enterococcus spp. (16%),
– Bacterioides fragilis (20%) – Gordon and Nivatvongs 2007

25. Wright WF. Infectious
diseases perspective of
anorectal abscess and
fistula-in-ano disease.
Am J Med Sci. 2016;351
(4):427–434.

26. Diagnosis

27. Diagnosis
• History
– Either acute or chronic phase
– anorectal abscess:
• Pain with swelling
• Predisposing diarrhea
• Bleeding per rectum
– Fistula-in-ano:
• Discharge
• Pain (34%)
• Swelling
• Bleeding
• diarrhea

28. Diagnosis
• Physical examination
– Anorectal abscess:
• Redness
• Heat
• Swelling – not in intersphincteric abscess
• pain
• Loss of function
• Mass when PR (mostly impossible to PR)
• Pus exuding
• Inguinal LN enlargement

29. Diagnosis
• Physical Examination
– Fistula-in-ano:
• 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

30. Gordon PH, Nivatvongs S. Principles and practice of surgery for the colon, rectum, and
anus. 3rd ed. New york: Informa healthcare USA, 2007.

31. Diagnosis
• Physical Examination:
– Goodsall’s rule:
• Accurate in only posterior external opening
– More distant from anal verge, more complex of
fistula
– Palpate skin to feel the cord in superficial fistula
– PR: pit of internal opening might be palpable
(herniation sign)
– Probing: feather-like touch to prevent false
channel

32. Gordon PH, Nivatvongs S. Principles and practice of surgery for the colon, rectum, and
anus. 3rd ed. New york: Informa healthcare USA, 2007.

34. Diagnosis
• Physical examination:
– Anoscopy and sigmoidoscopy: the must
• Identify internal opening
• Distinguish between rectal or anal canal opening
• Examine rectal mucosa if proctocolitis is suspected

35. Diagnosis
• Investigation:
– Fistulography
• Evaluate recurrent or extrasphincteric fistula
• Difficult to interpret
– Ultrasonography: endoanal US
• Assess recurrent fistula
• Good in intersphincteric and transphincteric fistula
– MRI
– BE and colonoscopy: indicated in Hx of IBD

36. Gordon PH, Nivatvongs S.
Principles and practice of
surgery for the colon, rectum,
and anus. 3rd ed. New york:
Informa healthcare USA,
2007.

37. Anorectal Abscess

38. Gordon PH, Nivatvongs S. Principles and practice of surgery for the colon, rectum, and
anus. 3rd ed. New york: Informa healthcare USA, 2007.

39. Treatment
• Drainage
• Role of antibiotics

40. Treatment: Drainage
• Principles:
– Adequately drained
– Cruciate incision or removing ellipse of skin over
the abscess
– Can be under LA, RA, or GA (for perianal and
ischioanal abscess)
– Drain closed to anal verge if possible to shorten
subsequent fistula tract
– No need of packing except bleeding

41. Gordon PH,
Nivatvongs S.
Principles and
practice of surgery
for the colon,
rectum, and anus.
3rd ed. New york:
Informa healthcare
USA, 2007.

42. Treatment: Drainage
• Perianal and ishioanal abscess:
– As same as abcess other parts of the body

43. Fischer JE, editor. Fischer’s Mastery of Surgery. 6th ed. Philadelphia: Lippincott Williams
& Wilkins, 2012.

44. Treatment: Drainage
• Intersphincteric abscess:
– Intersphincteric approach
– With or without division of internal anal sphincter
– Placement of the mushroom catheter
– With or without marsupialization

45. Treatment: Drainage
• Supralevator abscess:
– First, determine the origin:
• ischioanal
• Intersphincteric
• Pelvic: diverticulitis, Crohn’s disease, appendicitis
– Pelvic origin drainage:
• Rectal lumen
• Ischioanal fossa
• Abdominal wall

46. Create extrasphincteric fistula
Create suprasphincteric
fistula
Fischer JE, editor. Fischer’s
Mastery of Surgery. 6th ed.
Philadelphia: Lippincott
Williams & Wilkins, 2012.

47. Fischer JE, editor. Fischer’s Mastery of Surgery. 6th ed. Philadelphia: Lippincott Williams
& Wilkins, 2012.

48. Treatment: Drainage
• Horseshoe abscess:
– Circumferential spread along intersphincteric
plane, ischioanal fossa, or supralevator plane
– Ideal treatment: posterior drainage with
counterincisions both ischioanal fossa
– Hanley’s technique: Primary posterior midline
fistulotomy
– Modified Hanley’s: preserving all sphincters with
rubber seton

49. Gordon PH, Nivatvongs S. Principles and practice of surgery for the colon, rectum, and
anus. 3rd ed. New york: Informa healthcare USA, 2007.

50. Gordon PH, Nivatvongs S. Principles and practice of surgery for the colon, rectum, and
anus. 3rd ed. New york: Informa healthcare USA, 2007.

51. Treatment: Drainage
• Recurrent abscess:
– Major causes:
• Failure to provide adequate drainage
• Undrained pus
• Undiagnosed fistulous tract
– Extra-anal causes must be considered:
hidradenitis suppurativa or infected pilonidal cyst

52. Role of Antibiotics
• Unnecessary in uncomplicated case
• No role of antibiotic alone treatment
• Conditions that antibiotics have the role:
– Extensive cellulitis
– Systemic signs of infection (sepsis)
– Immunocompromised host: DM, valvular heart
disease, HIV
– Atypical microbes: TB, actinomycosis

53. Roles of Antibiotics
• No role of routine swab culture due to low
documentation
• Which one:
– Bowel-derived or skin-derived?
– Metronidazole
– Ceftriaxone
– Augmentin

54. Postoperative Care
• Regular diet
• Warm sitz bath tid-qid
• Bulk-forming agent: psyllium seed preparation
• Analgesics
• Advise to come back early if the pain is not
diminished

55. Fistula-in-ano

56. Brunicardi FC et
al. Schwartz’s
Principles of
Surgery. 10th ed.
McGraw-Hill
Education, 2015.

57. Gordon PH, Nivatvongs S.
Principles and practice of
surgery for the colon, rectum,
and anus. 3rd ed. New york:
Informa healthcare USA,
2007.

58. Rakinic J. Benign anorectal surgery management. Advances in Surgery. 2018:52;179-204.

59. Indications for Operation
• Recommended unless contraindication:
compromise anal incontinence
• Control active underlying diseases before
repair: TB and IBD
• Neglect fistulas may result in repeated
abscesses and persistent drainage

60. Principles of Treatment
• Cure the fistula with
– lowest recurrent
– minimal alteration of continence
– shortest period of time
• Identify primary opening of the tract
• Establish relationship of the tract to puborectalis
• Divide least muscle
• Seek of side tracts
• Look for underlying disease

61. Techniques
• Tract identification
• Fistulotomy
• Fistulectomy
• LIFT
• Seton
• Endorectal advancement flap
• Fibrin glue
• The modern treatment: fistula plug, fistula laser
closure, video-assisted anal fistula treatment,
adipose-derived stem cell

62. Tract Identification
• Gently probing
• Methylene blue (1:10) injection
• Hydrogen peroxide injection

63. Pigot F. Treatment of anal fistula and abscess. J Visc Surg. 2015:152;s23-s29.

64. Pigot F. Treatment of anal fistula and abscess. J Visc Surg. 2015:152;s23-s29.

65. Fistulotomy
• For simple intersphincteric fistula and low
transphincteric fistula
• Lowest recurrence rate
• techniques:
– Probe the tract
– Divide the tract by sliding scapel along grooved
probe director
– Curette and send granulation tissue for pathology
– Marsupialization to encourage healing

66. Pigot F. Treatment of anal fistula and abscess. J Visc Surg. 2015:152;s23-s29.

67. Gordon PH, Nivatvongs S. Principles and practice of surgery for the colon, rectum, and anus. 3rd ed. New york:
Informa healthcare USA, 2007.

68. Parks Fistulectomy
• Core out external opening
• Fistulotomy until expose internal anal
sphincter
• Unsatisfactory result

69. Gordon PH, Nivatvongs S. Principles and practice of surgery for the colon, rectum, and
anus. 3rd ed. New york: Informa healthcare USA, 2007.

70. Gordon PH, Nivatvongs S. Principles and practice of surgery for the colon, rectum, and
anus. 3rd ed. New york: Informa healthcare USA, 2007.

71. Gordon PH, Nivatvongs S. Principles and practice of surgery for the colon, rectum, and
anus. 3rd ed. New york: Informa healthcare USA, 2007.

72. Fistulectomy: Disadvantages
• longer operating time
• wider surgical wound
• Prolonged time of healing
• tripled incidence of incontinence

73. Not different

74. LIFT
• Ligation of Inter Sphincteric Fistula Tract
• Described by Prof. Arun Rojanasakul and
colleagues in 2007
• Sphincter-preserving procedure
• Good for well-forming transphincteric fistula
• Based on closure of the internal opening and
removal of the tract through the
intersphincteric approach

75. LIFT
• Essential steps:
– incision at the intersphincteric groove
– identification of the intersphincteric tract
– ligation of intersphincteric tract close to the
internal opening
– removal of intersphincteric tract
– scraping out all granulation tissue in the rest of
the fistulous tract
– suturing of the defect at the external sphincter
muscle

76. http://drrajatgoel.com/wp-content/uploads/2015/08/lift.jpg

77. Rojanasakul A. LIFT procedure: a simplified technique for fistula-in-ano. Tech
coloproctol. 2009:13;237-240.

78. Seton
• Drain placed through a fistula to
– Maintain drainage
– Induce fibrosis
• Good for high transphincteric fistula
• Cutting seton: converting high type to low one
by sequential tightening
• Noncutting seton: loose loop to maintain
drainage

79. Wolff BG et al. The ASCRS textbook of colon and rectal surgery. Springer science +
business media, 2007.

80. Rakinic J. Benign anorectal surgery management. Advances in Surgery. 2018:52;179-
204.

81. Seton
• Cutting seton
– Lower portion of internal sphincter is cut to reach
external sphincter
– Insert material (silk, vascular loop) to encircle
sphincter muscle
– Tie the loop in multiple knots
– Tighten the knot regularly to slowly cut the
sphincter
– 8 week later, remaining external sphincter is
divided

82. Rectal Advancement Flap
• Success rate 90%

83. Wolff BG et al. The ASCRS textbook of colon and rectal surgery. Springer science +
business media, 2007.

84. Dermal Island Flap Anoplasty
Gordon PH, Nivatvongs S. Principles and practice of surgery for the colon, rectum, and
anus. 3rd ed. New york: Informa healthcare USA, 2007.

85. Complications
• Urinary retention
• hemorrhage
• incontinence
• acute external thrombosed hemorrhoids
• cellulitis
• inadequate drainage and pocketing
• fecal impaction
• recurrent fistulas: failure to identify and treat orifice
• Rectovaginal fistulas
• persistent sinus
• bridging
• stricture

86. Postoperative Care
• Prevention of the contact and premature healing
of opposing skin edges
• Regular diet
• Analgesics
• Warm sitz bath tid
• Bulk-forming laxative
• Patient may experience fecal leak but if anorectal
ring is preserved, it will be normal in 10 days

87. Special Considerations
• Primary closure of anorectal abscess
– Drainage and curettage to destroy granulation
with antibiotics
– More recurrent abscess and fistula
– Need further evaluation

88. Special Consideration
• Superficial fistula
– Some not associated with cryptoglandular
infection
– Occur in hemorrhoidectomy patient
– Treatment: fistulotomy

89. Special Consideration
• Primary VS Secondary Fistulotomy in anorectal
abscess
– Primary:
• eradicate origin of infectious process
• Lower recurrence
• Higher incontinence
• May result in false passage when probing
• Not all anorectal abscess develops fistula
• Meta-analysis did not conclude the answer

90. Special Consideration
• How much muscle may be divided?:
– No universal answer
– Depends on primary sphincter function
– As a general rule, whole of internal sphincter and
most of external sphincter can be cut without
incontinence
– Using anal manometry

91. Special Consideration
• Primary anal sphincter reconstruction after
fistulotomy/fistulectomy (FIPS):
– First, Hang the muscle
– Fistulotomy/fistulectomy
– 2-layer Suture muscle with dexon 3-0
– Wound closure

92. Conclusion
• Anorectal abscess and fistula-in-ano are
mainly from cryptoglandular infection which
can be simultaneously
• Treatment depends on location and anal
sphincter function
• Anorectal abscess: drainage without
antibiotics
• Fistula-in-ano: get rid of granulation with
sphincter function preservation

93. References
Gordon PH, Nivatvongs S. Principles and practice of surgery for the colon,
rectum, and anus. 3rd ed. New york: Informa healthcare USA, 2007.
Netter FH. Atlas of human anatomy. Philadelphia: Elsevier, 2009.
Fischer JE, editor. Fischer’s Mastery of Surgery. 6th ed. Philadelphia: Lippincott
Williams & Wilkins, 2012.
Wolff BG et al. The ASCRS textbook of colon and rectal surgery. Springer
science + business media, 2007.
Brunicardi FC et al. Schwartz’s Principles of Surgery. 10th ed. McGraw-Hill
Education, 2015.

94. References
Lee JM, Kim NK. Essential Anatomy of the Anorectum for Colorectal Surgeons
Focused on the Gross Anatomy and Histologic Findings. Ann Coloproctol
2018;34(2):59-71 https://doi.org/10.3393/ac.2017.12.15
Wright WF. Infectious diseases perspective of anorectal abscess and fistula-in-
ano disease. Am J Med Sci. 2016;351 (4):427–434.
Lohsiriwat V. Anorectal emergencies. World J Gastroenterol 2016 July 14;
22(26): 5867-5878
Limura E, Giordano P. Modern management of anal fistula. World J
Gastroenterol 2015 January 7; 21(1): 12-20.

95. References
Amato A, Bottini C, De Nardi P, Giamundo P, Lauretta A, Luc AR, et al.
Evaluation and management of perianal abscess and anal fistula: a consensus
statement developed by the Italian Society of Colorectal Surgery (SICCR). Tech
Coloproctol (2015) 19:595–606.
Vogel JD, Johnson EK, Morris AM, Paquette I, Saclarides TJ, Feingold DL, et al.
Clinical Practice Guideline for the Management of Anorectal Abscess, Fistula-
in-Ano, and Rectovaginal Fistula. Dis Colon Rectum 2016; 59: 1117–1133.
Seow-En I, Ngu J. Routine operative swab cultures and post-operative
antibiotic use for uncomplicated perianal abscesses are unnecessary. ANZ J
Surg. 2017:87;356-359.
Pigot F. Treatment of anal fistula and abscess. J Visc Surg. 2015:152;s23-s29.

96. References
Rojanasakul A. LIFT procedure: a simplified technique for fistula-in-ano. Tech
coloproctol. 2009:13;237-240.
Schmidt SZ, Perdawood SK. Management of anal fistula by ligation of the
intersphincteric fistula tract – a systematic review. Dan Med J. 2014:61(12);1-
8.
Quah HM, Tang CL, Eu KW, Chan SYE, Samuel M. Meta-analysis of randomized
clinical trials comparing drainage alone vs primary sphincter-cutting
procedures for anorectal abscess–fistula. Int J Colorectal Dis:2006:21;602–
609.
Rakinic J. Benign anorectal surgery management. Advances in Surgery.
2018:52;179-204.

97. References
Xu Y, Liang S, Tang W. Meta-analysis of randomized clinical trials comparing
fistulectomy versus fistulotomy for low anal fistula. SpringerPlus.
2016:5(1722);1-6.
Perez F, Arroyo A, Serrano P, Candela F, Perez MT, Calpena R, et al. Prospective
clinical and manometric study of fistulotomy with primary sphincter
reconstruction in the management of recurrent complex fistula-in-ano. Int J
Colorectal Dis.2006:21;522-526. DOI 10.1007/s00384-005-0045-x
Perez F, Arroyo A, Serrano P, Candela F, Perez MT, Calpena R, et al.
Randomized clinical and manometric study of advancement flap versus
fistulotomy with sphincter reconstruction in the management of complex
fistula-in-ano. The American Journal of Surgery 192 (2006) 34–40

98. References
Ratto C, Litta F, Donisi L, Parello A. Fistulotomy or fistulectomy and primary
sphincteroplasty for anal fistula (FIPS): a systematic review. Tech Coloproctol
(2015) 19:391–400