By Ritha Belizaire, MD, FACS, FASCRS | Board-Certified General and Colorectal Surgeon

Quick Insights

An anal fistula is a small tunnel between the inside of the anal canal and the skin near the anus. Most start after an anal abscess (a pocket of infection). Fistulas rarely heal on their own, but they are very treatable. The right operation depends on how much of the sphincter muscle the tunnel crosses, because protecting bowel control is just as important as healing the fistula.

Key Takeaways

• About 1 in 3 people who have an anal abscess drained will go on to develop a fistula.
• Simple fistulas are usually cured with a fistulotomy, a short outpatient procedure.
• Complex fistulas need a sphincter-sparing approach, such as a seton, LIFT, or advancement flap.
• Fistulas linked to Crohn's disease are treated with surgery and medicine together.

What Is an Anal Fistula?

Just inside the anus are small glands. When one gets blocked and infected, it forms an abscess. The abscess pushes outward to drain, and the path it takes can stay open as a tunnel. That tunnel is a fistula.

Many of my patients come in after an abscess was drained in an emergency room or urgent care, only to find that the area keeps draining or the swelling keeps coming back. That pattern is a strong clue that a fistula has formed.

Symptoms

• Drainage of pus, blood, or fluid from a small opening near the anus
• Pain, swelling, or a tender bump that comes and goes
• Skin irritation from constant moisture
• Fever or feeling unwell during a flare
• An abscess that keeps coming back in the same spot

How an Anal Fistula Is Diagnosed

Most fistulas can be found with a careful office exam. For fistulas that are recurrent, complex, or related to Crohn's disease, I often order a pelvic MRI. It maps the tunnel and shows how it relates to the sphincter muscles, which helps me choose the safest operation.

Simple vs. Complex Fistulas

• Simple fistula: crosses little or no sphincter muscle. These are the most common.
• Complex fistula: crosses a large part of the sphincter, has more than one branch, comes back after surgery, or is linked to Crohn's disease, radiation, or a prior injury. In women, a fistula in the front of the anal canal is also treated with extra caution.

Treatment Options

The American Society of Colon and Rectal Surgeons (ASCRS) guidelines support matching the operation to the fistula's anatomy. Here is how I think about the options:

• Fistulotomy: the tunnel is opened and allowed to heal from the inside out. For simple fistulas in patients with normal bowel control, this is the standard treatment and has the highest cure rate.
• Seton: a soft surgical thread placed through the tunnel to keep it draining and calm the infection. A seton is often the first stage before a final repair, and it can be a long-term solution for some patients with Crohn's disease.
• LIFT procedure: the tunnel is tied off and removed through the space between the 2 sphincter muscles, without cutting either one. You can read more in my article on the LIFT procedure.
• Advancement flap: healthy tissue from inside the rectum is moved to cover the inner opening of the tunnel.

You may read about fistula plugs and fibrin glue online. The ASCRS guidelines describe them as relatively ineffective, so I rarely recommend them.

Fistulas and Crohn's Disease

A fistula is sometimes the first sign of Crohn's disease. When Crohn's is involved, surgery alone usually isn't enough. The best results come from combining a seton or repair with medical treatment from your gastroenterologist. I work closely with your GI doctor to plan both.

Rectovaginal fistulas, a connection between the rectum and vagina, are less common. They can follow childbirth, Crohn's disease, or prior surgery, and they need a specialized repair plan.

Recovery

• Most fistula procedures are outpatient. You go home the same day.
• Most people return to desk work within a few days.
• Expect some drainage for a few weeks. Sitz baths and a gauze pad help.
• Fiber and plenty of water keep bowel movements soft while you heal.
• Follow-up visits matter. Some fistulas need a second step to fully heal.

When to See a Colorectal Surgeon

Make an appointment if you have drainage near the anus that won't stop, an abscess that keeps returning, or a fistula that came back after a prior repair. If you have fever, spreading redness, or severe pain, get seen the same day, because a new abscess needs prompt drainage.

Fistulas are common and nothing to be embarrassed about. My office offers nitrous oxide as a comfort option for some in-office procedures.

Schedule a Consultation

If you're dealing with any of these symptoms, you don't have to wait. Call my Houston office at 832-979-5670 to request a same-day or next-day appointment. My office is at 427 W. 20th Street, Suite 710, in Houston Heights, and I operate at several hospitals across Houston.

Medical Disclaimer

This article is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always talk with your physician about your own situation.

Frequently Asked Questions

Will an anal fistula heal on its own?

Almost never. Antibiotics can calm a flare, but the tunnel usually stays. Most fistulas need a procedure to heal for good.

Will fistula surgery affect my bowel control?

Protecting your bowel control is my first priority. For simple fistulas, the risk is low. For complex fistulas, I use sphincter-sparing techniques such as a seton, LIFT, or advancement flap.

What is a seton, and how long does it stay in?

A seton is a soft thread that keeps the fistula draining so infection doesn't build up. It usually stays in for at least several weeks before the next step. For some patients with Crohn's disease, it stays longer.

Can an anal fistula come back after surgery?

Yes, especially complex fistulas. If yours comes back, there are still good options, and a second opinion can help map the best next step.