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An anal fissure is a small tear that happens on the surface of the skin or
mucosa of the anus as the result of an injury. The injury could be caused by hard
stools or simply by straining excessively (constipation).
Symptoms
The anus is a very sensitive area with a lot of nerve endings, so even a very
small injury can cause severe pain. The pain starts suddenly and can be
constant and excruciating. In milder cases it may happen only when the patient
has a bowel movement, settling minutes or hours later. There might be
occasionally a small amount of bleeding.
The pain can be so severe that the patient will not tolerate any form of
examination. The history of severe anal pain of sudden onset which does not
allow clinical examination usually suggests a fissure. Many doctors will prescribe
medication in this case (see below) although in some cases an EUA (Examination
Under Anaesthetic) will be required to confirm the diagnosis.
Once the pain has started it causes severe spasm of the anal sphincter muscles.
The spasm aggravates the pain and also reduces the blood supply in the area.
Blood supply is crucial for good healing. Decreased blood supply together with
constant contamination by bacteria from the anus have as result delay in healing.
The acute fissure can thus become chronic.
Chronic fissures can accumulate around them an amount of painful reactive scar
tissue which forms a little lump (fibroepithelial polyp).
Treatment
The treatment aims to help the healing of the fissure. The main way of achieving
that is by relaxation of the muscle spasm and improvement of the blood supply of
the area.
Medication used for this purpose is in the form of creams (GTN cream 0.2% or
Diltiazem cream 2%) or tablets (nifedipine). All those medications release as
active substance a molecule called Nitric Oxide which results in relaxation of
the anal muscles and dilatation of the blood vessels with improvement of
the blood supply. The initial course required is 6-8 weeks but some chronic
fissures may need 2 or 3 courses to settle.
All the above medications, and in particular the GTN cream cause dilatation in
other vessels of the body and can give strong headaches as side effect. This
headache will respond usually to common painkillers such as paracetamol and
will settle after a few days. If it persists, diltiazem cream has been shown to cause
less headache than GTN cream.
The role of Surgery
The great majority of anal fissures will not require surgery. However, when a
fissure has become chronic and has developed a painful fibrotic polyp next to it, it
is sometimes required to perform surgery in order to relieve the patient from the
pain.
The surgery aims to relax the muscles and thus improve the blood supply. This is
achieved by sphincterotomy (a cut of the internal sphincter muscle) or anal
stretch (stretching of both the internal and external sphincter muscles). If tender
scar tissue is present this is removed (fissurectomy).
In rare cases, if the above surgical treatment fails more complex surgery may be
required. This is called anoplasty or creation of advancement flap and involves
covering of the fissure with skin and/or anal mucosa. This is a delicate operation
performed only by specialist colorectal surgeons.
In most cases surgery can be successful in relieving the pain, however it should
be decided only if all medical treatment has failed and only if the patient has
intolerable pain. This is because, even if performed technically correctly, any
surgery that involves cutting or stretching the anal muscles may occasionally
result in incontinence. Incontinence for wind will happen in about 5-10% of
cases, while faecal incontinence can happen in approximately 2% of operations.
Incontinence after anal surgery is more common in women who have had multiple
child births. This is because sometimes there is a latent, undiagnosed, injury of
the anal sphincter which has occurred during delivery. Muscles of young women
are usually strong and can cope even when injured so there are no symptoms.
However a further surgical “injury” by sphincterotomy or anal stretch may result in
unexpected incontininece.
Anal Fissure