What Is an Anal Fistula?

An anal fistula is a small tunnel that forms between the inside of the anus and the skin nearby. It often develops after an infection in an anal gland creates an abscess that does not heal completely.

This condition can cause ongoing discomfort, drainage, and irritation around the anus. Anal fistulas usually require medical treatment to prevent repeated infections and improve healing.

Most anal fistulas begin after an infected anal gland forms an abscess. Certain health conditions can also increase the risk, including Crohn’s disease and other inflammatory bowel diseases. Prior surgery, injury, or radiation treatment in the pelvic area may also contribute.

Symptoms

Symptoms can range from mild irritation to significant pain. Some people notice symptoms that come and go, especially if the fistula continues to drain.

Common symptoms include:

• Pain or pressure near the anus
• Swelling or tenderness
• Drainage of pus or fluid
• Redness or irritated skin
• Fever or chills during infection
• Recurrent anal abscesses
• Discomfort with bowel movements

How Is It Diagnosed?

A healthcare provider will begin with a discussion about your symptoms and a physical exam. In many cases, the fistula opening can be seen or felt during the exam.

Additional testing may help determine the location and depth of the fistula. Your provider may recommend:

• Anoscopy to examine the anal canal
• MRI imaging
• Ultrasound of the anal area
• Examination under anesthesia for more complex cases

These tests help guide treatment and protect the muscles involved in bowel control.

How Is It Treated?

Anal fistulas usually do not heal on their own, and surgery is often needed. Treatment depends on the location of the fistula and whether nearby muscles are involved.

Treatment options may include:

• Antibiotics to treat infection
• Fistulotomy to open and heal the tunnel
• Seton placement to help drainage and healing
• Fistula plugs or special surgical sealants
• Reconstructive procedures for more complex fistulas

For people with Crohn’s disease, medication to reduce inflammation may also be part of treatment.

Recovery varies based on the procedure performed. Mild discomfort and drainage during healing are common. Your provider may recommend warm baths, a high-fiber diet, extra fluids, and stool softeners to make recovery more comfortable.