Anal Fistula and Anal Abscess

UW Health Colon and Rectal Surgery specialists in Madison, Wisconsin provide comprehensive evaluation and surgical treatment of diseases of the colon, rectum and anus.


Anal abscesses and fistulas are often related conditions.


Inside the anus are small glands that can become clogged when an infection develops from bacteria or foreign matter that has entered the tisse. When the glands become infected, an abscess can develop. Certain conditions, such as colitis or other intestinal inflammations can increase the risk of abscesses developing.


After an abscess has been drained, a tunnel may persist connecting the site of the abscess to the skin. This is called a fistula. Fistulas develop in about 50 percent of all abscess cases, and there is no way to predict when one might develop. Typically fistulas develop four to six weeks after an abscess is drained, and can even develop months or years later.


Symptoms of an Abscess or Fistula


An abscess may cause:

  • Pain and swelling around the anus
  • Fatigue
  • Fevers
  • Chills

A fistula may cause:

  • Irritation of the skin around the anus
  • Drainage of pus
  • Fever
  • A general feeling of being unwell

Treatment for Abscesses


Abscesses are treated by making an opening in the skin near the anus to drain the pus from the infected cavity. This is typically performed in the physician's office using just a local anesthetic.


Patients who are prone to more serious infections, such as those with suppressed immune systems, may require hospitalization for an abscess. A large or deep abscess may also require hospitlization to treat.


Antibiotics are not an effective treatment because they do not penetrate the fluid within an abscess.


Treatment for Fistulas


Surgery is often necessary to cure an anal fistula and should be performed by a specialist in colon and rectal surgery due to the potential for complication.


Fistula surgery is typically performed on an outpatient basis, though deep fistulas may require a brief hospital stay. During surgery, the internal and external openings of the tunnel are joined, allowing the fistula to heal from the inside out.


If the fistual or abscess heal properly, typically the problem will not return.