What is an Anal Fistula?

An anal fistula is an abnormal tunnel between the inside of the anal canal and the skin around the anus. It usually develops after an anal abscess that has not fully healed. Symptoms include persistent discharge, pain and recurrent perianal abscesses. Surgery is almost always needed as fistulas rarely heal spontaneously.

Classification

• Intersphincteric — passes between the internal and external sphincters (most common, ~70%)
• Trans-sphincteric — crosses through the external sphincter
• Suprasphincteric — passes above the sphincter complex (complex, rare)
• Extrasphincteric — bypasses sphincters entirely (rare, usually iatrogenic)

Treatment Options

• Fistulotomy (Lay-Open) — for low simple fistulas; the tract is opened and laid flat to heal from the inside. Success rate >95%. Risk to sphincter minimal for low fistulas.
• Seton Placement — a thread through the fistula tract for high or complex fistulas; drains infection and allows staged surgery.
• LIFT Procedure (Ligation of Intersphincteric Fistula Tract) — sphincter-preserving; the fistula tract is tied off in the intersphincteric space. Success rate 60–80%.
• Mucosal Advancement Flap — for complex or recurrent fistulas; the internal opening is covered with a flap of healthy rectal mucosa.
• Fibrin Glue / Bioprosthetic Plug — minimally invasive; best for simple fistulas where other options are unsuitable.