Anal fistulas are small tunnels that form from inside the anal canal to the outside skin around the anus. Anal fistulas are usually formed from infected anal glands that create an abscess, which drains by creating a fistula or passageway. This passageway can secrete pus, blood, or stool, and can cause severe pain around the anus.
Surgical drainage is the most common treatment for anal fistulas, but some fistulas can be treated without surgery.
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What Are Anal Fistulas?
Anal fistulas, also called fistula-in-ano, are small passages connecting infected anal glands inside the anal canal to the outside skin where the infection has drained. Anal fistulas are usually the result of anal glands becoming blocked and infected. A blocked gland fills with fluid and creates an abscess in the mucous-secreting gland in the anal canal. As the abscess drains out through the outside skin, it can form a tunnel or fistula.
An abscess does not always become a fistula. A fistula develops in up to 50% of all abscess cases. There is no way to predict if a fistula will develop or not. If drainage persists for two to three months, the diagnosis of anal fistula is made.
Although benign, anal fistulas can cause serious discomfort, pain, and embarrassment. It is important to seek treatment for an anal fistula so that it does not become more infected or severe.
What causes anal fistulas?
Anal fistulas are most commonly caused by abscesses in the anal canal. An abscess forms when a small gland just inside the anus becomes infected with bacteria or stool trapped in the gland.
Some conditions can make these types of infections more common, such as:
- Colitis.
- Constipation.
- Diarrhea.
- Other inflammation of the intestine.
After an abscess has been drained, a passage may remain between the anal gland and the skin, resulting in a fistula. If the gland does not heal, there will be persistent drainage through the passage. If the outside opening of the fistula heals first, a recurrent abscess may develop.
Anal fistula risk factors
The key risk factor for developing an anal fistula is having an anal abscess. Half of anal abscesses progress to anal fistulas.
Other conditions that can increase your risk for developing an anal fistula include:
- Cancer.
- Chronic diarrhea.
- Colitis.
- Crohn’s disease.
- Diabetes.
- Hyperlipidemia (high levels of lipids or lipoproteins in the blood).
- Infections around the anus.
- Obesity.
- Previous anal abscess.
- Radiation or surgery for anal cancer.
- Sedentary lifestyle.
- Trauma.
Anal fistulas are more common in men and adults over age 40, but can occur in people of all ages, depending on their risk factors and health status.
Complications of anal fistulas
Unfortunately, anal fistulas can recur after they’ve been drained and treated. Recurrence typically happens if surgery didn’t heal completely or could be caused by an underlying condition. Some people experience fecal incontinence – or the inability to hold in gas or stool – after anal fistula surgery.
How can I reduce my risks of anal fistulas?
It’s important to know that some anal fistulas are caused by underlying conditions or unforeseen circumstances that you would not be able to predict or prevent. However, there are some lifestyle changes you can make to reduce your risk of developing an anal fistula.
These lifestyle guidelines include:
- Having an active lifestyle — Anal fistulas are more likely to develop in people who live a sedentary lifestyle or are sitting for long periods of time every day. If you work at a desk job or spend a lot of your day sitting, take frequent breaks to stand up and walk around as much as you can. This helps take pressure off the anal area and lowers the risk of developing a fistula.
- Having healthy bowel movements—Constipation and straining while going to the bathroom can aggravate a fistula or contribute to the development of a new one. It’s important to talk with your doctor if you experience irregular or infrequent bowel movements and feel the need to strain during them. Drinking water, eating fiber-rich foods, and staying active can also help promote more regular bowel movements.
- Maintaining a healthy weight – Obesity is a risk factor for anal fistulas because of the added pressure of weight in the anal area. Talk with your doctor to make sure you are eating a rich, colorful diet that includes enough fruits, vegetables, protein, and healthy fats to keep you energized and healthy.
- Quitting smoking – Smoking can prolong any healing process and can interfere with your body’s ability to fight infections. If you are experiencing an anal fistula, it is best to quit smoking to give your body the best chance at fully healing and avoiding a recurring fistula.
- Seeking medical attention quickly – Do not wait if you experience pain, redness, swelling, or discharge around the anus. Talk to your doctor to receive prompt medical care before the infection worsens.
- Using proper hygiene – It is critical to wash your hands with warm water and soap after every bowel movement and to thoroughly wash your body to reduce the risk of infection in the anal area.
What Are the Signs and Symptoms of Anal Fistulas?
The most common symptoms of an anal fistula are:
- Drainage of blood, pus, mucus, or stool from an opening near the anus.
- Fever, chills, or feeling ill.
- Frequent anal abscesses.
- Pain or tenderness in the rectum or anus, usually when sitting or having bowel movement.
- Swelling, redness, or irritation around the anus.
When should I see a doctor about my anal fistula symptoms?
If you are experiencing any of the above symptoms, it is important to promptly talk with your doctor to receive appropriate treatment.
How Do You Diagnose Anal Fistulas?
Your doctor will most likely discuss your symptoms and medical history, then perform a physical examination to diagnose an anal fistula. This exam will include looking at, around, and possibly inside your anus to find signs of a fistula.
Typically, the external opening of an anal fistula can be seen on the skin surrounding the anus. Your doctor will want to find where the internal opening originates inside the anal canal, as understanding the infection’s path is important for providing appropriate treatment.
Your doctor may also order imaging tests to determine the course of the fistula and best treatment option.
These tests include:
- Anal examination under anesthesia — This may be recommended so a surgeon can thoroughly examine the fistula without causing too much discomfort while awake.
- CT scan — This test may be ordered to see a more detailed map or the tunnel’s path and openings.
- Endoscopic — This imaging test uses high-frequency sound waves to view the muscles and tissues around the anus and identify the fistula’s path.
- Fistulography — This test uses injected contrast to find the fistula’s path using x-ray.
- MRI — This test can show more detailed images of the tunnel’s path and the other muscles and tissues around the anus.
How Do You Treat Anal Fistulas?
If you are diagnosed with an anal abscess that has not yet become a fistula, it can be treated in a doctor’s office using a local anesthetic. A doctor will drain the pus through an opening made in the skin near the anus.
A large or deep abscess may require drainage in the operating room. Hospitalization may be necessary for people susceptible to more serious infections, such as those with diabetes or decreased immunity.
Otherwise, most anal abscesses that become anal fistulas must be treated by surgical drainage. Here’s what you need to know to be prepared.
Surgery for anal fistulas
If the fistula is not too deep or severe, it can be treated using a fistulotomy. This procedure involves cutting a small portion of the anal sphincter muscle to open the passage, joining the external and internal opening, and converting the passage into a groove that will then heal from the inside out. Most fistula surgeries can be performed on an outpatient basis.
If the fistula involves too much sphincter muscle, a two-stage procedure or more complicated repair may be necessary. One example is the ligation of the intersphincteric fistula tract (LIFT) repair, which involves a silk or latex string holding the fistula tunnel open. Weeks later, the surgeon removes the infected tissue and stitches up the internal opening.
After fistula surgery, you may experience mild to moderate discomfort for the first week that can be controlled with pain pills. There will be no limitations on activity. Soak the affected area in warm water three or four times a day. Stool softeners may also be recommended.
You may need to wear a gauze pad to prevent the drainage from soiling your clothes. Bowel movements will not affect healing.
How effective is anal fistula treatment?
While anal fistula surgery is commonly successful, that does not mean that anal abscesses or fistulas will not recur. It is important to practice healthy habits – such as good hygiene, diet, and exercise – to prevent anal fistulas from reappearing. If symptoms begin again, call your doctor.
