Abnormal connection between the anal canal and the perianal skin

Aetiology

• Majority arise from delayed/inadequate treatment of anorectal abscesses
• Patient may have Crohn’s, carcinoma or TB as an underlying pathology

Clinical features

• Painful tender swellings
• Discharge onto the perineum, including mucus, blood, pus, or faeces

Investigations

• EUA: of anorectum
• Proctoscopy: to visualise the opening of the tract
• MRI: can be used in complex fistula

Management

• Surgically excised then drained
• Followed up with antibiotics