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What is an anal fistula?

An anal fistula is a small tunnel that connects an abscess, an infected cavity in the anus, to an opening on the skin around the anus.

The anus is the external opening through which feces are expelled from the body. Just inside the anus are a number of small glands that make mucus. Occasionally, these glands get clogged and can become infected, leading to an abscess. About half of these abscesses may develop into a fistula.

 

What causes an anal fistula?

The leading causes of an anal fistula are clogged anal glands and anal abscesses. Other, much less common, conditions that can cause an anal fistula include:

  • Crohn’s disease (an inflammatory disease of the intestine)
  • Radiation (treatment for cancer)
  • Trauma
  • Sexually transmitted diseases
  • Tuberculosis
  • Diverticulitis (a disease in which small pouches form in the large intestine and become inflamed)
  • Cancer

 

What are the symptoms of an anal fistula?

The signs and symptoms of an anal fistula include:

  • Frequent anal abscesses
  • Pain and swelling around the anus
  • Bloody or foul-smelling drainage (pus) from an opening around the anus. The pain may decrease after the fistula drains.
  • Irritation of the skin around the anus from drainage
  • Pain with bowel movements
  • Bleeding
  • Fever, chills and a general feeling of fatigue

You should see your doctor if you notice any of these symptoms.

 

How is an anal fistula diagnosed?

Your doctor can usually diagnose an anal fistula by examining the area around the anus. He or she will look for an opening (the fistula tract) on the skin. The doctor will then try to determine how deep the tract is, and the direction in which it is going. In many cases, there will be drainage from the external opening.

Some fistulas may not be visible on the skin's surface. In this case, your physician may need to perform additional tests:

  • An anoscopy is a procedure in which a special instrument is used to see inside your anus and rectum.
  • Your physician may also order an ultrasound or MRI of the anal area to get a better view of the fistula tract.
  • Sometimes your surgeon will need to examine you in the operating room (called exam under anesthesia) to diagnose the fistula.

If a fistula is found, your physician may also want to do further tests to see if the condition is related to Crohn's disease, an inflammatory disease of the intestine. About 25% of people with Crohn's disease develop fistulas. Among these studies are blood tests, X-rays and colonoscopy. A colonoscopy is a procedure in which a flexible, lighted instrument is inserted into the colon via the anus. It is performed under conscious sedation, a type of light anesthetic.

What is an anal fistula?

An anal fistula is a small tunnel that connects an abscess, an infected cavity in the anus, to an opening on the skin around the anus.

The anus is the external opening through which feces are expelled from the body. Just inside the anus are a number of small glands that make mucus. Occasionally, these glands get clogged and can become infected, leading to an abscess. About half of these abscesses may develop into a fistula.

 

What causes an anal fistula?

The leading causes of an anal fistula are clogged anal glands and anal abscesses. Other, much less common, conditions that can cause an anal fistula include:

  • Crohn’s disease (an inflammatory disease of the intestine)
  • Radiation (treatment for cancer)
  • Trauma
  • Sexually transmitted diseases
  • Tuberculosis
  • Diverticulitis (a disease in which small pouches form in the large intestine and become inflamed)
  • Cancer

 

What are the symptoms of an anal fistula?

The signs and symptoms of an anal fistula include:

  • Frequent anal abscesses
  • Pain and swelling around the anus
  • Bloody or foul-smelling drainage (pus) from an opening around the anus. The pain may decrease after the fistula drains.
  • Irritation of the skin around the anus from drainage
  • Pain with bowel movements
  • Bleeding
  • Fever, chills and a general feeling of fatigue

You should see your doctor if you notice any of these symptoms.

 

How is an anal fistula diagnosed?

Your doctor can usually diagnose an anal fistula by examining the area around the anus. He or she will look for an opening (the fistula tract) on the skin. The doctor will then try to determine how deep the tract is, and the direction in which it is going. In many cases, there will be drainage from the external opening.

Some fistulas may not be visible on the skin's surface. In this case, your physician may need to perform additional tests:

  • An anoscopy is a procedure in which a special instrument is used to see inside your anus and rectum.
  • Your physician may also order an ultrasound or MRI of the anal area to get a better view of the fistula tract.
  • Sometimes your surgeon will need to examine you in the operating room (called exam under anesthesia) to diagnose the fistula.

If a fistula is found, your physician may also want to do further tests to see if the condition is related to Crohn's disease, an inflammatory disease of the intestine. About 25% of people with Crohn's disease develop fistulas. Among these studies are blood tests, X-rays and colonoscopy. A colonoscopy is a procedure in which a flexible, lighted instrument is inserted into the colon via the anus. It is performed under conscious sedation, a type of light anesthetic.

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