INCIDENCE
Common.
Females > males
Most at middle age.
Risk factors
Constipation. Comorbidities: Often goes together with
haemorrhoids.
May occur in females after a pregnancy (anteriorly).
AETIOLOGY
Trauma
Usually occur whilst passing a hard stool.
- this is not always the case, and may follow diarrhoea or normal
stool passage. Hypertonia of the internal anal
sphincter is common in these pts
- relationship between this and fissures is unclear
Partly related to Western diet.
Infection
Occasionally seen in some STDs.
Inflammation
Crohn's.
Iatrogenic
Removing too much skin during a haemorrhoid op may mean anal
stenosis and tearing of this when a hard motion is passed.
1. Anal fissures are elongated tears in the long axis of the
mucocutaneous lining of the anal canal (anoderm), often extending
from the dentate line to the anal margin.
Usually (>90%) in the posterior midline.
The posterior rectal wall curves forward from hollow of sacrum
- then turns sharply backwards at the anal canal.
- during defecation the pressure
of the stool is mainly against posterior anal tissue.
- when a scybalous mass is being expelled, the overlying skin is
stretched.
- and thus may tear.
- eliptical anatomy of the canal also means less support given in
antero-posterior axis.
2. Experimental evidence suggests relative
deficiency of posterior anal blood flow may contribute to
persistence of the fissure.
- ie is a watershed area.
Although hard stools commonly implicated, explosive liquid stool can
cause same result.
Occur anteriorly in 10% of female fissures cf 1% male fissures
3. 90%+ pts have high mean anal
resting pressure.
- spasm; implicated in poor healing.
- hence sphincterotomy, widens the anal canal.
Acute vs chronic.
Acute
<6 weeks
Accompanying spasm of the anal sphincter muscle.
Many of these heal spontaneously.
Chronicity A self perpetuating cycle is
established:
It is painful to defecate
- the patient is reluctant to do so
- the stools become firmer
- the fissure worsens
Pain is attributed to internal sphincter spasm.
Over time, distal skin may become oedematous and enlarged / form a
skin tag / sentinel pile.
- the cephalad anal papilla may also enlarge.
- these changes attributed to chronic low-grade infection.
Pts who develop chronic fissures may be susceptible.
- abnormal spasm after dilation of the sphincter, abnormal baseline
pressure .
Post-partum
In women post-partum the damaged pelvic floor and attenuated
perineal body means a lack of support of the anal mucous membrane.
Hence anterior anal fissures may occur.
Recent Doppler studies suggest that a perpetuating post-traumatic
low blood supply and relative ischaemia may contribute to these.
Complications Infection / abscess
Invasive infection may accompany chronic disease.
Intersphincteric abscess formation possible, with perianal abscess
or rupture into anal canal. Multiple fissures
May complicate skin disease, scratching, IBD, anal receptive
intercourse
Symptoms Local Pain
The dominant symptom.
- squamous epithelium is highly sensitive.
Sharp and severe; often described as 'tearing'.
Starts during defecation.
- as the ulcer is stretched.
Lasts for minutes to hours.
Then ceases suddenly.
Intermittent remissions of days or weeks.
The patient thus avoids defecating, becoming constipated following
this regimen: "a large dose of senna on Saturday night, then retire
to the toilet on Sunday morning with a bottle of whisky and the
newspaper" (B&L).
Bleeding
Usual.
Passage of bright red blood following the stool / streaks on the
paper.
Usually slight.
Change in bowel habit
Occasionally pts have diarrhoea / alternating bowel habit.
Other
Pruritis, swelling, perhaps prolapse associated.
Slight mucus discharge in chronic cases.
Signs Observe
Put in left lateral position, bum over edge of table.
Gently part the buttocks to reveal the fissure.
The pt often has a 'shy anus'
- ie you get a fleeting glimpse of the fissure before sphincter
contraction withdraws it from view.
Fissures are usually located in the midline posteriorly (90%).
- or sometimes anteriorly (10%) in females, particularly after
pregnancy.
- if located away from here, consider (eg) crohns, STD,
hidradenitis, as is atypical.
Acute
Extends through skin of anal margin into anal canal.
A little inflammatory induration or oedema at edges.
Chronic
Inflamed and indurated margins.
The base consists of either scar or the lower border of the internal
sphincter.
- sphincter has a characteristic whitish fibre appearance.
The ulcer is canoe-shaped.
A sentinel ('guarding') skin tag is often seen at the anal margin.
- this develops from heaped up granulated oedematous tissue.
- a hypertrophied anal papilla may be visible at the upper end of
the anal canal.
The spasmodic internal sphincter may be organically contracted due
to infiltration of fibrous tissue.
Palpate
Feels like a buttonhole.
PR is unnecessary - extremely painful and associated with anal
spasm.
If you must perform PR then apply 5% xylocaine to cotton wool and
leave in place for 5 minutes.
- better to leave it until later
Differential STDs Fissure of Crohn's disease
Usually deep with indolent edges, may be multiple and at atypical
sites, and are usually less painful. Anal SCCs
(In early stages)
Excise if any doubt.
An atypical appearance should
question the diagnosis.
- lateral location, extension to the verge / above the dentate,
extension through the sphincter = atypical.
Aim is to completely relax the
internal sphincter.
This relieves pain.
And allows slow healing.
Conservative
Usually conducted first due to complications of sphincterotomy.
Often only a temporary solution.
Best for patients presenting acutely (within 3-6 weeks of symptom
onset).
Four week regimen:
1. Warm sitz baths b.d. -
e.g. once after defecation, once before bed
- decrease anal canal pressures. e.
2. Stool softeners (fibre
agents best)
--> Rates of healing are high for new fissures; less if chronic - also advise on dietary fibre, adequate hydration; avoiding
constipation
Chemical Sphincterotomy Appropriate (in addition to above).
Cochrane Review 2009 : good evidence for chance of cure with
conservative therapies as follows:
(All have similar efficacy)
3. Glyceryl trinitrate
bd-tds (0.2% cream)
- releases NO, relaxant and vasodilation.
- patient should lie down when applying the ointment as side effects
are significant eg headache.
- use a glove, pea sized piece on fingers to limit side effects.
- 50% heal but 50% of those relapse; sentinel pile (chronic fissure)
helps predict failure.
- starts working in a few days, but typically 4-6 weeks, so wait
that long for review.
- continue for another 4-6 weeks if working.
4. Topical diltiazem (1-2%
tds for 4 weeks) has similar efficacy and fewer side effects.
- requires a compounding pharmacy.
5. Botox is not widely used
despite good logic behind it.
- 100u diluted in 2mL of normal saline; 20-40u injected into IAS
base at either side of fissure
- 50% healing, but again high recurrence.
- needs further work to define how to use optimally.
Warn some risk of partial incontinence during therapy.
Nothing else shown better than placebo including topical steroids or
lignocaine
Operative
For patients failing medical therapy
Operative management remains in no danger of becoming outdated at
present.
EUA and colonoscopy Rule out associated problems
Lord's procedure
Anal stretch is dangerous and no longer practiced
Tailored lateral internal sphincterotomy.
98% healing; 1% incontinence
Do not perform in IBD
See procedure Advancement flap
- if all else fails, can consider
- higher risk of incontinence and more complex