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Anal fissure

What is an anal fissure?

An anal fissure is a tear or split in the lining of the anus. They can be difficult to see unless careful inspection of the anus is performed with good lighting and parting of the buttocks

What causes anal fissures?

Anal fissures commonly arise from the trauma of passing a large hard stool. This trauma causes a split (i.e. fissure) of the anus. The sphincter then goes in to spasm which impairs blood flow to the wound thereby causing delayed healing or non-healing.

Other less common causes are Crohn's disease, chronic diarrhoea, and other trauma to the anal region.

What are the symptoms?

Anal fissures are typically extremely painful. Patients describe it as a sharp pain especially when having a bowel motion. The typical description of the pain is "like passing razors blades / shards of glass out of the anus".

Bright red bleeding can also occur, though is usually low volume and on the toilet paper only.

What investigations are required?

Careful history taking followed by a dedicated careful inspection of the anus with good lighting and an experienced eye are often all that is needed. If the diagnosis is made, a digit rectal examination generally is not performed as it is exquisitely painful and not tolerated well. A colonoscopy may be recommended down the track to exclude any sinister causes.

What are the treatment options?

There are a cocktail of treatments required to give the best chance of fissure healing without surgery. These are:

  1. Regular non-constipating simple analgesics (e.g. paracetamol and ibuprofen) for pain relief
  2. Regular fibre supplements such as Metamucil or Benefiber
  3. Stronger laxatives may be needed (e.g. Movicol)
  4. Warm sitz baths twice a day and after bowel motions
  5. Topical Rectogesic ointment three times a day for six weeks

Regular analgesics will help ease the discomfort, and the fibre supplements and laxatives keep the stool soft to minimise further trauma to the anus. The warm baths help relax the anal sphincter which typically goes into spasm, causing increased pain and reduced blood flow preventing healing.

What is Rectogesic and what are the side effects?

Rectogesic is a topical ointment containing 0.2% glyceryl trinitrate. This medication causes relaxation of the internal anal sphincter which improves blood flow allowing healing.

Side effects of this medication are common and include headaches and light-headedness / dizziness due to lowering of blood pressure. It is important to apply the ointment to the anus using a gloved finger (or Glad Wrap over the finger) to prevent absorption through the finger. If headaches are an issue, taking paracetamol 30mins prior to application of Rectogesic can be useful. If light-headedness occurs, lying down for 30mins after applying the ointment can help. The longer the ointment is used for, the less side effects occur as the body becomes more tolerant to the medication.

What are the surgical options if non-operative treatment fails?

If topical medication and stool softening fails to heal the fissure, the next options are Botox injection or lateral internal sphincterotomy.

How does Botox work?

Botox injection would usually be performed in the operating theatre along with careful inspection of the anorectum under brief general anaesthetic. The Botox is injected in between the internal and external anal sphincter muscles. The Botox causes temporary relaxation of the internal anal sphincter, thereby allowing improved blood flow and hopefully healing. The effects from Botox last approximately 3 months then wear off. There is usually no incontinence with this treatment.

What is a lateral internal sphincterotomy?

This is a surgical procedure to cut a small amount of the internal anal sphincter. It is irreversible, however is the most effective way to heal the fissure with the least likelihood of fissure recurrence. There can be permanent side effects from this procedure including incontinence to flatus or liquid stool. I generally reserve this procedure for those who have failed serious attempts at non-operative management of the fissure and who have also failed to heal after Botox.

Will my anal fissure come back?

The anal fissure can return if ongoing constipation occurs. It is therefore important to not only address the fissure, but treat any underlying bowel disorder and constipation to prevent recurrence of the anal fissure.