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Anal Fissure

1. Definition

2. Incidence

• Common referral to colorectal clinic (up to 15%). 1 in 350 people in European Union.
• Mainly seen in young adults

3. Aetiology

• No known causative factor proven
• Ischaemia is thought to be the primary cause
• Constipation may be result of fissure and not cause!

4. Sex

• Affects both sexes equally

5. Pathology

• 90% of fissures are found in the posterior midline
• Multiple fissures in the lateral position must raise awareness of other causes such as
  • IBD esp Crohn's disease
  • Malignancy
  • Tuberculosis
  • HIV
  • Syphilis
• Thought to be an ischaemic ulcer: poor blood supply in the posterior midline is further reduced by high pressure from the internal anal sphincter

6. Symptoms

• Pain on defaecation - patients describe passing stool as like "passing broken glass"
• PR bleeding - typically on the paper, not mixed with the stool
• Pruritis
• Mucous discharge

7. Diagnosis

• Diagnosis is made by the history and examination
• Place patient in left lateral decubitus
• Do not perform rectal examination as patient will not be able to tolerate due to pain 
• Ask patient to bear down as if passing motion
• Note location and orientation of fissure to the midline
• Most fissures can now be seen in the posterior midline
• Look for signs of a chronic anal fissure
  • Sentinel haemorrhoid or skin tag

8. Management

8.1 Conservative Management

• Attempt 6-8 weeks of conservative management first
• Use a regimen of
  • Dietary modification - high fibre diet, increase fluid intake
  • Stool softener e.g. lactulose
  • Warm Baths

8.1.1 Chemical sphincterotomy

• GTN 0.2% ointment topically applied twice daily for 6 weeks.
  • Produces local relaxation of smooth muscle, promoting healing
  • Some patients are intolerant of the headache and should be warned of this side effect prior to prescription
  • for further reading regarding GTN use in anal fissure click here
• Diltiazem topical gel
  • Alternative to GTN
• Botulinum (Botox) toxin injection

  Injected into the internal anal sphincter Causes denervation and rapidly paralyses the muscle Reduces resting pressure of the anal sphincter Expensive + dose and site not fully established

8.2 Surgical Management

• Surgery is performed in those whom fail optimum conservative management
• Lateral sphincterotomy +/- excision of fissure
  • Patient placed in lithotomy
  • Intersphincteric groove palpated
  • Internal sphincter identified medial to the external sphincter
  • Cut the internal sphincter the length of the fissure itself
  • If a chronic fissure
    • excise fissure + sentinel pile - send to histology
    • perform lateral sphincterotomy
  • Patient must be warned of soiling + nightime incontinence

   

9. Suggested further reading