An anal fissure can be defined as a tear in the squamous mucosal lining of the anal canal.
They mostly occur on the posterior aspect of the anal canal. Anterior fissures often follow parturition in females.
- High-pressure fissures - ischaemia due to high pressure in anal sphincter causes the fissure.
- Low-pressure fissures - tends to happen in postpartum women.
🔢 Classification
It can be defined as:
- Acute - <6 weeks
- Chronic - >6 weeks
- Primary - no underlying disease present
- Secondary - underlying disease such as IBD
⚠️ Risk factors
The main causes are inflammation and trauma. Some major risk factors are:
- Constipation
- Dehydration
- IBD
- Chronic diarrhoea
😷 Clinical features and symptoms
- Intense post-defecatory pain is the most common and defining feature. The pain may be disproportionate to the size of the fissure.
- Bleeding of fresh, bright red blood on wiping or after defecation.
- Itching
Fissures are visible/palpable upon DRE. However, patients may often decline a DRE due to the pain and may require an examination under anaesthesia (EUA).
Fissures are most prominent posteriorly (90%) and anteriorly (10%). A lateral anal fissure suggests a secondary cause and requires further investigation.
We may see a sentinel pile often at 6 and 12 o’clock positions. These are small external lump associated with the tear.
🕵🏽♂️ Differential diagnosis
Haemorrhoids, Crohn’s disease, ulcerative colitis, anal cancer.
🧰 Management
- Analgesia
- Topical anaesthetics
- 🥇 Dietary management (such as increasing fluid and fibre intake) if less than 1 week.
- Laxatives
- If this fails, one can use a GTN cream or diltiazem cream (a CCB) to increase blood flow to the region and relax the internal anal sphincter to promote healing, reduce pain and apply less pressure on the fissure. Diltiazem is better tolerated but GTN is used as it is just cheap. This is for high-pressure fissures.
🥈 Topical glyceryl trinitrate is first-line treatment for a chronic anal fissure.
