An anal fistula is an abnormal channel or opening between the anal glands and the skin. The contents of the anal glands can flow through the unnatural channel and collect in the skin in the anal area. Anal fistulas can become very painful, but do not usually cause any significant harm to the patient. However, an anal fistula can be dangerous if formed stool passes into the fistula and gets trapped in the tissues. It is possible for an infection to occur and it is possible to develop septicemia if a systemic infection occurs.

An anal fistula can occur in the location where there was once an anal abscess. An anal abscess occurs when the duct to an anal gland becomes blocked. Anal glands produce fluid that drains into the rectum to make defecation easier. When the fluid is blocked in the ducts, an infection can form in that area, which may result in an abscess. A fistula can form when an abscess doesn't heal properly. A fistula can open outside of the rectum.

Fistulas can also be caused by underlying conditions such as irritable bowel syndrome or Crohn's disease. These conditions can cause ulcerations in the bowel tract which can eventually turn into fistulas.

It is fairly easy to diagnose anal fistulas because there are openings found outside of the anus. The doctor can inspect the anal region and see the openings. You are most likely to have an anal fistula if you have had an anal abscess.

Anoscope and fistula probe are usually used to evaluate the type of anal fistula. In some cases ultrasound examination is helpful to visualize the fistulas. When there are multiple or complex fistulas, a special X-ray, called fistulography, and MRI may be ordered.

A sigmoidoscopy or a colonoscopy may also be done. If there is no prior history of diseases or conditions of the digestive system, then sigmoidoscopy may be a first line diagnostic evaluation. If the patient is age 50 or more, then colonoscopy is performed to rule out cancer or any other type of disease or condition of the colon.

There are different treatment options for anal fistulas, depending on how severe they are:

Fistula plug

In some cases, no invasive surgery is needed. Patients with relatively simple fistulas may be treated by injection of a special type of plasma protein glue or insertion of a plug into the fistula.


the fistula is opened up and the lining of the fistula is scraped. The fistula is secured in an open position so that it can heal.


There are different types of anal fistulas; they are called low anal fistulas and high anal fistulas. If an anal fistula is low it is in the area of anal sphincter. Conversely, a high fistula occurs in the part of the anal canal or rectum which is well above the sphincter muscle.