Anal fistula

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at January 15, 2016
StartDiseasesAnal fistula

An anal fistula is a small tunnel connecting an anal abscess to an opening in the skin near the anus. It can cause patients significant physical and psychological discomfort but is a treatable condition.


Definition & Facts

Anal fistula occurs when there is a connection between the surface of the skin and an infected anal gland or anal abscess. A fistula usually develops when the original abscess is surgically or spontaneously opened. Anal fistulas can occur between a vein and an artery or any other potential tissue or organ combination.

A fistula refers to an abnormal connection between body organs and tissues that do not usually connect. Although fistulas can occur in various parts of the body, anal fistulas are the most common types of fistulas.

Symptoms & Complaints

A fistula usually looks like a red, inflamed spot that may be oozing some pus. Patients with fistula will encounter smelly drainage that consists of either blood, feces, and pus from an opening near the anus. Pain around the anus, anal bleeding, and anal inflammation are also symptoms. Other symptoms associated with fistulas include fatigue, fever, irritation, redness, and discomfort.

A complication associated with anal fistula is that infections may occur around open body cavities and organs. In addition, if the fistula remains untreated, it could grow and cause more damage to other body tissues and organs including the rectum, intestines, bladder, and vagina.


Common causes of anal fistula include trauma triggered by anal sexual intercourse and surgery. Some surgical procedures can unintentionally create a fistula between the bladder and the rectum. Anal fistulas may also be caused by autoimmune diseases that trigger inflammation of the bowel. Examples include Crohn’s disease and ulcerative colitis. Inflammation can cause there to be weak spots between the rectum and other organs. Bacterial infections may also cause anal fistulas.

Diagnosis & Tests

Diagnosing an anal fistula involves performing a physical exam and rectal examination. It starts with a doctor examining the anus and the surrounding areas for signs of a fistula. Once the doctor finds the opening of the fistula, he or she can be able to work out where the path of the fistula lies. The fistula’s path often feels like a hard cord-like structure under the skin.

The doctor may also perform a rectal examination to find the fistula’s internal opening and secondary tracts that may be branching off the fistula. The rectal examination usually involves placing a finger into the anus and then up the rectum. Certain tools such as proctoscopes and fistula probes are usually used in anal fistula diagnosis. Other types of tests used in fistula diagnosis include a type of ultrasound called an anal endosonography, MRI, and CT scan.

Treatment & Therapy

Anal fistula causes great embarrassment to patients, which may make some patients reluctant to seek speedy medical attention. However, there are various treatment options for anal fistula including antibiotics, surgery and anal fistula plugs.

Some types of anal fistulas can be treated with an antibiotic, which cures the infection and heals the fistula. Surgery is often recommended if the antibiotic treatment fails. The main aim of surgery treatment for a fistula is to drain the fistula.

Although surgery is an effective treatment option, an anal fistula can recur and become infected despite the surgery. In such cases, a fistula plug may be inserted to help heal the fistula and prevent contaminants from infecting the open areas around the fistula. A fistula plug is a collagen protein injected into the fistula opening to seal it shut and prevent infections.

Prevention & Prophylaxis

One of the most effective ways of preventing anal fistula is to prevent constipation. There are many ways of preventing constipation including adding more fiber to the diet and drinking adequate amounts of water each day. Fiber supplement powders can work just as well as natural fibrous foods.

In addition, people can decrease their risk for anal fistulas by using gentle anal cleaning techniques, keeping the anal area dry by using powder to help absorb moisture, and changing underwear frequently.