Fissure-in-ano - Disorders of the rectum and anus

Fissure-in-ano

Definition

An anal fissure is a tear in the skin lining the lower anal canal.

Aetiology

1.     Primary fissure-in-ano are idiopathic, they are generally posterior. Patients often report the onset of symptoms when passing hard, constipated stool.

2.     Secondary fissure-in-ano are seen in inflammatory bowel disease when they are often multiple and may occur anywhere around the anal circumference.

Pathophysiology

Fissures are longitudinal tears, which develop into canoe shaped ulcers involving the lower third of the internal sphincter. Swelling and inflammation at the anal verge may form a sentinel pile (haemorrhoid).

Clinical features

Severe burning pain on defecation that may last for hours so that defecation is avoided. The sentinel pile may be visible on examination, rectal examination is very painful and often impossible. Examination under anaesthesia (proctoscopy/sigmoidoscopy) allows diagnosis.

Complications

Infections may form a perianal abscess.

Management

Primary anal fissures may heal spontaneously. Refractory fissures may require surgical management. An incision is made into the perianal skin on one side of the anal canal and the internal sphincter is divided without entering the lumen.