Anal Fissure

Definition and diagnostic criteria

An anal fissure is a small tear in the lining of the anal canal, which can cause pain and bleeding during bowel movements. It is classified as acute if present for less than six weeks and chronic if it persists beyond six weeks. Chronic fissures may be accompanied by additional features such as a sentinel pile (a skin tag at the outer end of the fissure) or hypertrophied anal papilla.

Epidemiology

Anal fissures are a common proctologic condition, affecting all age groups but most prevalent in young and middle-aged adults. There is no significant gender predisposition. Anal fissures can occur in healthy individuals but are also associated with conditions such as inflammatory bowel disease, particularly Crohn’s disease, and anal trauma.

Diagnosis

Clinical features: The hallmark symptoms of anal fissures include severe pain during and after defecation, often described as sharp or burning, and bright red rectal bleeding, typically noticed on toilet paper or stool surface. Chronic fissures may present with a less intense but persistent pain and pruritus ani (itching). A physical examination reveals a longitudinal tear in the anus, usually located posteriorly in the midline, although anterior fissures are also common, particularly in women.

Investigations: Diagnosis is primarily clinical, based on history and physical examination, which includes visual inspection and gentle digital rectal examination (DRE). Anoscopy may be employed to further evaluate the fissure and rule out other conditions such as haemorrhoids or malignancies. In chronic cases or when atypical features are present, further investigations like sigmoidoscopy or colonoscopy might be indicated to exclude underlying pathologies like Crohn’s disease.

Treatment

Acute fissures: First-line treatment involves conservative management aimed at reducing anal sphincter spasm and promoting healing. This includes:

• Dietary modifications: High-fibre diet and increased fluid intake to soften stools.
• Laxatives: Bulk-forming laxatives like ispaghula husk to prevent constipation.
• Topical treatments: Anaesthetic creams (e.g., lidocaine) to alleviate pain and nitroglycerin ointment or calcium channel blockers (e.g., diltiazem) to reduce sphincter pressure and enhance blood flow to the fissure.

Chronic fissures: Chronic fissures often require more aggressive treatment:

• Topical treatments: Continued use of nitroglycerin or calcium channel blockers.
• Botulinum toxin injection: Into the internal anal sphincter to induce temporary paralysis and promote healing.
• Surgical intervention: Lateral internal sphincterotomy is considered the gold standard for refractory cases, offering high healing rates but with a small risk of faecal incontinence. Less invasive procedures, such as fissurectomy or anal advancement flap, may also be considered.

Prognosis

The prognosis for anal fissures is generally good with appropriate treatment. Acute fissures often heal within a few weeks with conservative measures. Chronic fissures can also heal with medical or surgical intervention, but recurrence rates vary. Long-term management focuses on preventing constipation and maintaining anal hygiene. Complications such as persistent pain, bleeding, and anal stenosis are rare but possible, particularly if treatment is delayed.