Chronic Anal Fissure

A chronic anal fissure persists beyond the normal acute healing period and develops structural changes including a sentinel skin tag, hypertrophied anal papilla and exposed internal sphincter fibres.

Persistent internal anal sphincter hypertonicity reduces anodermal perfusion and prevents healing.

Pain remains strongly associated with defaecation and may persist for hours.

Inspection may show:

• Deep posterior midline ulcer
• Visible internal sphincter fibres
• Sentinel tag
• Hypertrophied anal papilla

Diagnosis is clinical.

A chronic lateral fissure, multiple fissures or disease with atypical ulceration requires evaluation for secondary pathology.

Maintain soft formed stool using fibre and polyethylene glycol when needed.

First line pharmacological sphincter relaxation can use:

• Diltiazem 2% topical cream applied to the anal verge twice daily for approximately 6 to 8 weeks.

An alternative is:

• Glyceryl trinitrate 0.2% to 0.4% ointment applied twice daily for approximately 6 to 8 weeks. Diltiazem provides similar healing with fewer headaches than topical nitrates.

Botulinum toxin is useful after topical treatment failure or when avoiding sphincter division is important.

A commonly used total dose is:

• Botulinum toxin 20 to 60 units injected into the internal anal sphincter, divided between one or more sites. There is no single superior injection protocol.

Lateral internal sphincterotomy provides the highest healing rate and is appropriate for chronic primary fissure that persists despite medical treatment or in selected patients where definitive surgery is preferred. Divide only enough internal sphincter to reach approximately the proximal extent of the fissure rather than automatically dividing to the dentate line. Tailored sphincterotomy reduces unnecessary sphincter injury.

Avoid or use major caution with sphincterotomy in patients with baseline faecal incontinence, previous obstetric sphincter injury, inflammatory bowel disease or previous sphincter dividing anorectal surgery.

In these patients, fissurectomy with an advancement flap or botulinum toxin can preserve sphincter function. Healing after lateral internal sphincterotomy is approximately 88% to 100%, but continence risk must be considered individually.