Describe the surgical anatomy of anal canal.
List the types of Anal & Peri-anal diseases and their common
State Goodsall’s rule.
Describe the pathology, C/F, investigations, D/Ds and treatment –
3. Surgical Anatomy
The length of anal canal is about 4 cm (range, 3-5
cm), extends – rectum – analverge.
1/3rd - above & 2/3 - below the dentate line.
The anatomical anal canal extends from the
perineal skin to the linea dentata.
The surgical anal canal begins at the anorectal
junction ( anorectal ring ) and terminates at the
Anorectal ring - Puborectalis muscle , the deep
ES, conjoined longitudinal muscle and the highest
part of the IS. It is digitally palpable upon RE.
4. Surgical Anatomy
The dentate or pectinate line:
marks the transition point between columnar rectal
mucosa and squamous anoderm.
The anal transition zone:
1 to 2 cm of mucosa just proximal to the
dentate line shares histologic characteristics of
columnar, cuboidal, and squamous epithelium.
The columns of Morgagni:
The dentate line is surrounded by longitudinal
mucosal folds, known as the columns of Morgagni,
into which the anal crypts empty. (Source of
5. Surgical Anatomy
The anal sphincter is comprised of three layers:
Internal sphincter: continuance of the circular smooth
muscle of the rectum, involuntary and contracted
during rest, relaxes at defecation.
Intersphincteric space. Small anal glands are located
between the internal and external sphincters and
communicate with the anal crypts via anal ducts.
External sphincter: voluntary striated muscle, divided
in three layers that function as one unit.
Hemorrhoids basically means "blood flow" [Greek
'haima' meaning "blood" + 'rhoia' meaning "flow"].
Piles – Latin word – “Pila” – Ball.
Hemorrhoids are defined as the symptomatic
enlargement and distal displacement of the normal
“Anal cushions” – aggs. of blood vessels, smooth
muscles & elastic CT in submucosa – normally
reside – 3 positions.
Present concept – Weakening of lower end of ES –
12. Haemorrhoids - Aetiology
DIET & HABITS
Low fibre diet
Constipation & Hard stool
2 to trauma during defecation→ weakening of venous wall⁰
Pregnancy / ascites / pelvic tumor
Anal hypertonia / Ageing
Shearing forces acting on the anus lead to caudal
displacement of the anal cushions and mucosal trauma.
Excision of the pile masses up to base.
It can be done by 2 methods :-
OPEN METHOD – Milligan Morgan
CLOSED METHOD – Hill-Ferguson
17. Anal Fissure
An ulcer in the longitudinal axis of lower anal
Site – Midline / Posteriorly - Males
Superficial lesion / ends below the dentate line
Spasm & Contracture of IS – major role in fissure
Hard stool / Trauma
Increased sphincter tone
18. Anal Fissure - Types
It is a deep tear in the
lower anal skin with
severe sphincter spasm
– no oedema or
It presents with severe
pain and constipation.
- It has inflamed /
- Hypertrophied anal
papilla internally &
sentinel tag externally.
- Less painful.
- Sentinel Pile (‘sentinel’
- Skin enlarges and
appears like guarding
19. Anal Fissure – Treatment
Conservative initially –
Chemical agents – ointments
Lord’s dilatation ↓ GA
Surgery if above fails –
Lateral Anal Sphincterotomy
20. Fistula – in – ano
It is a track lined by granulation tissue which
connects perianal skin superficially to anal canal;
anorectum or rectum deeply.
Cryptoglandular - 90%
Non – cryptoglandular – 10%
Unusual infections (TB, chlamydia, actinomycosis)
22. Goodsall’s rule
Fistulas with an external opening in
relation to the anterior half of the anus is of
Fistulas with external openings in relation
to posterior half of the anus, has a curved
track may be of horse-shoe type, opens in
the midline posteriorly & may present with
multiple external opening all connected to
a single internal opening.
24. Anal abscess
Infected cavity filled with pus found near the anus.
Common organism – E.coli (60%).
Cryptoglandular origin – 95%.
Other conditions include fistula-in-ano (most
common), Crohn’s disesase, diabetes,
Usually produces a painful, throbbing swelling –
anal region. The patient often has swinging pyrexia.
Treatment is drainage of pus in first instance,
together with appropriate antibiotics.
Always look for a potential underlying problem.
26. Pruritis Ani
Intractable itching in and around the anus
Common, embarrasing condition / Skin is
reddened, hyperkeratotic, cracked & moist
Poor hygiene / Anal discharge / T V infection /
Parasites / Epidermophytosis
Allergic cause / Skin diseases -
Diabetes mellitus / Psychological cause
Proper cause should be assessed and treated.
Hygiene measures: toilet paper / soap water / cotton
underwear; calamine lotion; shaving.
Hydrocortisone: only in patients with dermatitis.
Strapping of the buttocks
27. Hidraenitis Suppurativa
A chronic suppurative condition of apocrine gland of skin.
Pathogenesis → Obst / Infection / Pustules / Fistula
Does not extend into dentate line or sphincter.
3x more common in women than men - Obesity
Sinus; scarred areas; discharge; skin changes; pain &
tenderness; foul smelling fluid are the presentations.
D / D – Crohn‘s disease; F-I-A; pilonidal sinus;
tuberculosis; actinomycosis; LGV.
Trt - In early stages, general measures: Weight ↓ /
Surgical intervention ranges from simple I&D to radical
excision of all apocrine gland-bearing skin with closure
by skin graft/rotation flap.
28. Anal Warts
It is most common sexually transmitted anal
It is common in homosexual men & caused by HPV.
Many are asymptomatic.
Pruritus, discharge, bleeding & pain are usual
O/E - Pinkish-white warts close to the anal margin
are seen. Later, the warts enlarge, coalesce and
carpet the skin.
Local application of 25% podophyllin cream.
Excision under LA / RA / GA.
29. Anal Intraepithelial Neoplasia - AIN
It is dysplasia of anal or perianal epidermis.
It is seen in individuals with HIV / HPV infection;
individual who do anorectal intercourse.
AIN I – Outer 1/3 - Low grade.
AIN II – Middle 1/3 – Low grade squamous intraepithelial
AIN III – Full thickness – High grade squamous
30% of anal warts will show AIN.
It is raised scaly white / pigmented / cracked lesion.
Biopsy confirms the disease.
Treatment: Excision / Topical imiquimod and oral
30. Malignant tumours
Anal malignant tumours are < 2% of large bowel tumors.
It can be below the dentate line (SCC - 80%); above the
dentate line (Basaloid / transitional / cloacogenic).
Causes - HPV infection / HIV infection / AIN / organ
transplant receipients / immunosuppression.
Usually present as a fungating or ulcerative growth,
which spreads to inguinal lymph nodes.
Early anal margin tumours were treated by Wide local
Nowadays, primary treatment [combined modality therapy
(CMT) / Nigro Regime [ RT – 3 weeks → CT (5-FU +
Mitomycin C or cisplatin → APR > 3 weeks ].
33. GOOD SALL’S RULE
Fistulas with an external opening in relation to the anterior half of the anus is of
Fistulas in relation to the posterior half of the anus has a curved track may be of
horse-shoe type and opens in the midline posteriorly.
There may be multiple external opening all connected to a single internal opening.
34. An exception to this rule occurs if an external anterior opening is
more than 3cm from anal margin. It is more likely to have an internal
opening in posterior midline.
Any fistula defying this rule should arouse the suspicion of
inflammatory bowel disease.
GOOD SALL’S RULE