Makindo Medical Notes

💡 Anal fissure is a common but very painful condition caused by a small tear in the mucosal lining of the anal canal. Although benign, it can have a major impact on quality of life due to severe pain during and after defaecation.

📘 About

• Small linear tear in the anoderm (anal canal mucosa).
• Classically located posteriorly in the midline.
• May be acute (heals within weeks) or chronic (persists >6 weeks with fibrosis or sentinel skin tag).

🧬 Aetiology

• 💥 Localised trauma: Most often from passage of large, hard stool (constipation).
• 🔄 Other causes: Insertion of foreign objects, sexual trauma, childbirth, inflammatory bowel disease (especially Crohn’s), chronic diarrhoea.

⚠️ Clinical Features

• 🔥 Severe pain on defaecation: Often described as “like passing broken glass.”
• ⌛ Persistent pain: Lasts minutes to hours afterwards, sometimes worse than expected for such a small lesion.
• 📍 Typical site: Posterior midline; anterior fissures are less common (consider Crohn’s if multiple or lateral).
• ❌ Exam tolerance: Patients may be unable to tolerate digital rectal exam due to pain.
• 💧 Bright red rectal bleeding often noted on toilet paper.

🧪 Investigations

• Primarily a clinical diagnosis.
• 🔬 Bloods (FBC, U&E, LFTs) if dehydration, anaemia, or systemic disease suspected.
• 📑 Examination under anaesthesia (EUA) with proctoscopy if pain prevents full exam or to exclude haemorrhoids / malignancy.

💊 Management

• 🥦 Lifestyle: High-fibre diet, hydration, stool softeners (e.g. Lactulose, Movicol) to reduce straining.
• 💊 Pain relief: Simple analgesia; warm sitz baths may soothe discomfort.
• 🧴 Topical agents:
  • Glyceryl trinitrate (GTN) ointment – relaxes internal sphincter, increases blood flow; applied twice daily for up to 8 weeks (common SE = headache).
  • Diltiazem 2% cream – calcium channel blocker alternative with fewer headaches.
• 💉 Botulinum toxin injection: Into the internal sphincter; useful if medical therapy fails.
• 🔪 Surgery: Lateral internal sphincterotomy (LIS) for chronic/refractory fissures – high success but risk of incontinence must be considered.

📚 References

• NHS: Anal Fissure Information
• Bowel Research UK