6. Gross structure of Rectum
• 12 cm in length
• Is a part of large bowel
• Commences at level sacral 3 vertebral body and follow the
curve of the sacrum and coccyx
• Is continuation of sigmoid colon at rectosigmoid junction.
• Extend from rectosigmoid junction to anal canal.
• Anorectal junction :
- Lies at level of pelvic floor
- Puborectalis muscle form a u-shaped sling at this
point.
- Perineal flexure annulates anorectal junction
8. 2 of Flexures
A. Lateral flexure divide by transverse rectal fold
1) Superior
- Convex to the right
2) Middle
- Convex to the left and most prominent
3) Inferior
- Convex to the right
9. • Antero – posterior flexure
- In the terminal part of rectum
- At the anorectal junction
- Here the rectum perforates the pelvic
diaphragm to become the anal canal.
10. Peritoneal Relations
a) Superior 1/3rd of rectum
- Covered by peritoneum on the anterior and
lateral surfaces.
b) Middle 1/3rd of rectum
- covered by peritoneum at the anterior surface
c) Inferior 1/3rd of rectum
- Subperitoneum or devoid of peritoneum
15. Anal Canal
Gross structure
* Terminal part of gastrointestinal tract
* Is approximately 3cm long
* Commences at anorectal junction and ends at anus
* Encircle by internal and external sphincter muscle
* Descends between perineal body and anococcygeal ligament
*Mucosal lining of superior has longitudinal ridge – anal columns
- Inferior ends of collumns joined by anal valves
- behind valves are small sinuses : anal sinuses
- anal glands (mucus) empty into anal sinuses
* Inferior end of anal valves forms an irregular line : dentate line
* Dentate line divides the superior portion of the anal canal, derived from
embryonic endoderm
19. Anal Fistula
• What is an anal fistula ?
- A fistula is defined as an abnormal communication between
two epithelial surfaces.
- Anal fistula is a communication between the anorectal canal
and the perianal skin that is lined with granulation tissue. It
may be useful to consider it is a tunnel during discussion with
patient.
20. Who gets anal fistula ?
• The prevalance of anal fistula is 1-2 per 10 000 of the
population in European studies, but this is probably
an underestimate, with many patients being
reluctant to present to medical services.
• Men are twices as likely to be affected, and it most
commonly presents around 40 years of age.
21. How do anorectal fistula develop?
• Most anal fistulas are idiophatic.
• Infection of glands in the intersphincteric space of anal
canal is thought to underlie both acute anorectal
abcesses and anal fistulas.
• The exact cause or mechanism of infection has not been
fully elucidated, but it spreads through pathways of least
resistance and in so doing creates a track.
• A recent review of perianal abcess and fistula quotes
a fistula formation rate of 26 – 37% after perianal
abscess .
22. How are fistulas classified?
• Classification and successful management of anal
fistula require expert knowledge of anorectal
anatomy. A variety of classification systems have
been described, but the most useful and widely
accepted classification is that described by Parks.
• The classification system is based on the relation
between the primary tract, the main tunnel that
constitutes the fistula and the sphincter muscles
around the anal canal.
23.
24. Classification of fistula :
1. Intersphinteric fistula :
Do not cross the external sphinter. Most
commonly they run directly from internal to
external opening across the distal internal
sphinter but may extend proximally in the
intersphincteric plane to end blindly with or
without an abscess, or enter the rectum at a
second internal opening.
25. 2. Trans-sphincteric fistulae :
Have a primary track that crosses both internal
and external sphincters and which then passes
through the ischiorectal fossa.
26. • 3. Suprasphincteric fistulae are very rare, are
thought by some to be iatrogenic and are
difficult to distinguish from high-level
transsphincteric tracks
4. Extrasphincteric fistulae run without specific
relation to the sphincters and usually result from
pelvic disease or trauma.
27.
28. Presentation
• Intermittent discharge
(purulent or bloody)
• Chronic or recurrent perianal pain, lump
(which increases until temporary relief
occurs when pus discharges)
• Pruritis ani
• Pervious episode of anorectal sepsis, surgery, radiotherapy and trauma.
29. Clinical Assessment
• History : Full medical history including obstetric,
gastrointestinal, anal surgical and continence are necessary.
Before any surgical procedure is carried out an EUA should
be performed.
• EUA: A full examination/inspection of the perineum followed by DRE &
Proctosigmoidoscopy.
– DRE examination - area of induration, fibrous tract and internal opening may be felt,
Follow palpable tract that feels like a cord-like structure below the skin.
– Proctosigmoidoscopic inspection - to evaluate the rectal mucosa for any
underlying disease process.
30. Key points to determine on EUA
• Site of internal opening.
• Site of external opening.
• The course of primary tract
• Presence of secondary extention.
• Sphincter strength.
• The presence of other condition complicating
the fistula.
31. Goodsall's Rule
used to indicate the likely position
of the internal opening according to
the position of the external
opening(s)
• If the external opening is
anterior to the line, the fistula
usually runs directly into the anal
canal.
• If the external opening is
posterior to the line, the fistula
usually curves to the posterior
midline of the anal canal.
32. Imaging in Fistula in ANO
a ) Fistulography
b) Endoanal ultrasound
c) MRI
37. Fistulotomy
It involves division of all structures
lying between internal and external
openings.
Applied mainly to low variety
intersphincteric and trans-
sphinceric fistula
39. Setons (Latin: seta = bristle) have been used in a variety of ways
in fistula surgery and it is important for surgeons to be clear
about what they are trying to achieve in a particular situation.
1. Uses of loose setons
a. For long-term palliation to avoid septic and painful
exacerbations by establishing effective drainage; most often in
Crohn’ disease.
b. Used before ‘advanced’ techniques (fistulectomy,
advancement flap, cutting seton)
40. 2. Uses of cutting setons
• Cutting setons aim to achieve the high fistula
eradication rates associated with fistulotomy
but without the degree of functional
impairment.
41. Fistula Plug
The biological fistula plug is manufactured from porcine small intestinal mucosa.
It is resistent to infection, does not induced a foreign body reaction.
It encourage host cells to populate it and fill the fistula track.
43. Advancement flap
Aim to stop the fistula tract communicating
with the bowel and cover the internal opening
with disease – free anorectal wall.
The procedure involves dissection of a full or
partial thickness flap of the proximal rectal
wall
Failure or ischemia of the flap may result in
the creationof a much larger defect. Most
surgeons quote a success rate of 30%
44. LIFT procedure
• Ligation of the Intersphinteric Fistula Tract
(LIFT) was first described in 2007.
• A skin incision is made between the internal
and external anal sphincters . The fistula tract
is exposed within the intersphinteric space
and subsequently ligated and divided.
47. References
• Bailey & Love's Short Practice of Surgery
• Netter's Atlas Of Human Anatomy (5th Ed.)
• BMJ Clinical review – Management of anal
fistula ( published 12/10/12)
