Anal fissures (Guidelines)

An anal fissure is a longitudinal tear in the anal canal running from dentate line to anal verge. Most (approximately 90%) are superficial and in the posterior midline.

The primary reason for their development is straining to pass stool coupled with a failure of the sphincter muscle to relax fully during evacuation.

If a fissure is lateral to the midline or deep with atypical appearance, this may point towards other aetiology eg, HIV, Malignancy.

The main symptom is anal pain provoked by defecation, which may last for hours. Patients may describe the sensation as like ‘passing broken glass’ when going to the toilet.

1. 50% of anal fissures will resolve completely with constipation management, sitz baths and dietary fibre supplementation.
   If necessary, a prescription of ispaghula husks (eg. Fybogel) may be issued. See resources: Bulk-forming laxatives.
2. When perianal pain is the overwhelming symptom, topical anaesthetics are less effective but can be used as adjuncts to the above measures. Lidocaine 5% ointment may be used for severe pain for a maximum of several days. See resources: Surface anaesthesia.
3. If the above measures are ineffective in managing symptoms, first line topical treatment is with Diltiazem 2% cream (unlicensed - available from special order manufacturers and a supply is kept as stock in Raigmore). A pea-sized amount should be applied to the skin of the anal verge twice daily for 8 weeks. It must be stressed to the patient that they should complete a full course of treatment and that attention must be paid to avoid constipation or straining during this period. See resources: Anal fissures.
4. Alternative topical treatment such as nitrates are more expensive, are associated with more side effects (up to 30% of patients report headache) and should generally be avoided unless there is a contraindication to diltiazem. Glyceryl Trinitrate 0.4% ointment (Rectogesic). Apply a small pea-sized amount to the site of the anal fissure twice daily until pain resolves, up to a maximum 8 weeks. See resources: Anal fissures.
5. A lack of response to the above measures should prompt a referral to secondary care for consideration of botulinum (Botox) injection or, in select cases, lateral sphincterotomy.