Anal fistula

Anal fistula (also known as fistula-in-ano) is an abnormal tunnel-like tract that forms between the inner lining of the anal canal and the skin near the anus. It most commonly develops as a consequence of a perianal abscess, where an infection in one of the small glands inside the anus spreads to form a collection of pus, which then drains or is surgically drained, leaving behind a persistent channel. The condition primarily affects the anorectal region and surrounding perianal soft tissues. Key symptoms include persistent or recurrent perianal discharge (which may be purulent or blood-tinged), pain around the anus that often worsens with sitting or bowel movements, swelling, skin irritation, and sometimes fever if secondary infection occurs. Patients may notice a visible external opening near the anus from which discharge drains. Anal fistulas can be classified based on their anatomical relationship to the anal sphincter muscles (intersphincteric, transsphincteric, suprasphincteric, or extrasphincteric). While most cases are cryptoglandular in origin, anal fistulas can also be associated with underlying conditions such as Crohn's disease, tuberculosis, radiation therapy, or prior pelvic surgery. The condition predominantly affects adults, with a higher incidence in males than females. Treatment is primarily surgical, as spontaneous healing is uncommon. Surgical options include fistulotomy (laying open the tract), seton placement (a thread or rubber band placed through the fistula to promote gradual drainage and healing), advancement flap procedures, ligation of the intersphincteric fistula tract (LIFT procedure), and fibrin glue or collagen plug insertion. The choice of procedure depends on the complexity and location of the fistula relative to the sphincter muscles, with the primary goal being to eradicate the fistula while preserving anal continence. Recurrence rates vary depending on fistula complexity and the surgical technique employed.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

Common questions about Anal fistula