An anorectal fistula is an epithelialized tract connecting the anus to the perirectal skin. Anorectal fistulas can occur in males and females of any age, with higher frequency in adult males; anorectal fistulas are less common in children.

The most common cause of an anorectal fistula is an anorectal abscess. Other underlying diseases, such as inflammatory bowel disease (mostly Crohn disease), tuberculosis, actinomycosis, and lymphogranuloma venereum can predispose patients to fistula formation in the perirectal / anal region. Additionally, foreign body instrumentation can result in anorectal fistulas.

Common symptoms and exam findings include anal pruritus, constipation, dyschezia, purulent rectal discharge, inflamed perianal skin, and fecal occult blood.

Treatment is typically surgery, along with management of any underlying disease process (eg, Crohn disease). Patients diagnosed with anorectal fistulas should anticipate needing cross-sectioning imaging (MRI or endoscopic ultrasound) and perhaps an examination in the operating room with anesthesia to fully characterize the fistula before potentially curative surgery. Maintaining fecal continence is a primary concern when operating on an anorectal fistula.