Anal Fistulas | Digestive Health Program | Loyola Medicine

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Anal Fistulas

Overview and Facts about Anal Fistulas

An anal fistula results from an anal abscess, which is an infected, pus-filled cavity near the anus. These abscesses form from an acute infection in internal anal glands that often result when bacteria or fecal matter clog the gland. The anal fistula is the tunnel that connects the clogged gland to the anal abscess and the abscess to the skin, where it drains.

Also called fistula-in-ano, anal fistulas always form under the skin. Sometimes they develop without an anal abscess and simply connect the infected anal gland to the skin near the rectum.

Signs and Symptoms of Anal Fistulas

Anal fistulas create a range of signs and symptoms. Some of the most common include:

  • Drainage from perianal skin
  • Fever
  • Pain near the anus
  • Painful urination
  • Rectal bleeding
  • Red skin near the anal opening, called perianal cellulitis
  • Trouble urinating

Causes and Risk Factors of Anal Fistulas

When the glands inside your anus get clogged, it allows bacteria to build up and create a pocket of infection. The area swells and fills with pus and liquid. As the abscess continues to grow, it eventually pushes its way to the skin, where it rips a hole somewhere near the anus and allows the infected interior to drain. This drainage canal is the fistula.

While most fistulas are a direct result of an anal abscess, fistulas can also form from tuberculosis, sexually transmitted diseases, or chronic bowel conditions. Other risk factors for anal fistulas include past trauma or radiation therapy to the anal area.

Tests and Diagnosis of Anal Fistulas

When a doctor suspects a digestive health issue like anal fistulas, they take a thorough health history, ask questions regarding anorectal symptoms, and perform a physical exam. They may palpitate the area, looking for inflammation and tenderness.

Because not all anal abscesses and fistulas have external symptoms, they may perform a digital rectal exam to look for the cause of rectal pain. When there are visible signs of draining, this test is often unnecessary.

Treatment and Care for Anal Fistulas

There is no medication to cure an anal fistula and they don’t heal on their own, even if the infection goes away. Fistulas left untreated can continue to fester and create an increased risk of cancer.

Most doctors recommend a fistulotomy, a simple surgical procedure to eliminate anal fistulas. The skin and muscles around the fistula are cut and allowed to heal from the inside out. Other times, a doctor may plug the fistula. If there are signs of infection before surgery, the doctor may place a tube, called a seton, into the opening to drain any fluid and pus.