An anal fissure is a small tear or cut in the lining of the anus. It can cause severe pain during and after bowel movements, as well as rectal bleeding. Anal fissures are common in both adults and children. They can be acute (lasting less than 6 weeks) or chronic (lasting more than 6 weeks). Early treatment helps to relieve symptoms and prevent chronic complications.
Causes
- Passing large or hard stools during constipation
- Frequent diarrhoea causing irritation of the anal lining
- Childbirth trauma
- Anal intercourse
- Inflammatory conditions like Crohn’s disease
- Rarely, infections such as syphilis, tuberculosis, or HIV
Pathophysiology
An anal fissure usually starts with trauma to the anoderm (skin around the anus), typically due to passing a hard stool. This leads to a tear, triggering a cycle of pain and internal anal sphincter spasm. The spasm reduces blood flow to the area, delaying healing and leading to a chronic fissure. In chronic cases, a sentinel pile (small skin tag) and hypertrophied papilla (enlarged anal gland) may develop.
Signs and Symptoms
- Sharp, burning pain during or after passing stool
- Bright red blood visible on the toilet paper or in the stool
- A visible crack or tear around the anus
- Itching or irritation around the anus
- Muscle spasms or tightness in the anal area
- A small lump near the fissure in chronic cases
Risk Factors
- Chronic constipation or straining
- Recurrent diarrhoea
- Pregnancy and vaginal delivery
- Sedentary lifestyle
- Low fibre diet
- History of inflammatory bowel disease
- Previous anal surgery
Investigation
- Clinical examination: Inspection of the anus is often sufficient to diagnose an anal fissure.
- Digital Rectal Examination (DRE): Usually avoided in acute fissures due to pain.
- Proctoscopy or Anoscopy: Helpful for better visualisation if tolerated
- Further investigations: Reserved for atypical fissures (lateral fissures, multiple fissures, or suspicion of underlying disease like Crohn’s). This may include colonoscopy, biopsy, or MRI if malignancy or complex disease is suspected.
Management
1. Non-Pharmacological Management
- Dietary changes: High-fibre diet to soften stools
- Adequate fluid intake: To prevent hard stools
- Good toilet habits: Avoid prolonged sitting and straining
- Sitz baths: Sitting in warm water for 10–15 minutes several times a day to relax the sphincter and promote healing
- Topical barrier creams: To protect the skin
2. Pharmacological Management
- Topical nitroglycerin 0.2% ointment: Helps relax the internal anal sphincter and improve blood flow
- Topical diltiazem 2% cream: Calcium channel blocker alternative with fewer side effects compared to nitroglycerin
- Botulinum toxin injections: For chronic fissures, to relax the sphincter muscle and aid healing
- Oral analgesics: Such as paracetamol or ibuprofen for pain relief
- Laxatives: To prevent constipation (bulk-forming or osmotic laxatives)
3. Surgical Management
- Lateral internal sphincterotomy (LIS): Gold standard for chronic fissures that do not respond to medical treatment. It involves making a small cut in the internal sphincter to reduce spasm and allow healing.
- Anal dilation (Lord’s procedure): Less commonly used due to higher risk of incontinence.
- Fissurectomy: Surgical removal of the fissure in some cases.
Complications
- Chronic anal fissure formation
- Development of a sentinel pile (skin tag)
- Fistula-in-ano if infection occurs
- Anal stenosis (narrowing of the anal canal) after repeated trauma or surgery
- Fecal incontinence after surgical procedures (rare with modern techniques)
References
- National Institute for Health and Care Excellence (NICE) Guidelines on Constipation and Haemorrhoids
- Royal College of Surgeons (RCS) Guidance on Management of Common Proctological Disorders
- British Society of Gastroenterology (BSG) Clinical Practice Guidelines
- General Medical Council (GMC) Good Medical Practice 2024