Perianal Abscess and Fistula

What Is a Perianal Abscess?

A perianal abscess is an infection around your anus that began in a mucous-secreting gland in the anal canal.

What Is a Perianal Fistula?

A perianal fistula, almost always the result of a previous abscess, is a small passage connecting the anal gland from which the abscess arose to the skin where the abscess was drained.

What Causes an Abscess?

An abscess results when a small gland just inside the anus becomes infected from bacteria or stool trapped in the gland. You did nothing to cause this infection. Certain conditions--constipation, diarrhea, colitis, or other inflammation of the intestine, for example--can sometimes make these infections more likely.

What Causes a Fistula?

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 this passage. If the outside opening of the fistula heals first, a recurrent abscess may develop.

What Are The Symptoms of an Abscess or Fistula?

Perianal abscesses are generally accompanied by intense anal pain and swelling. Fever is possible. Drainage of the abscess, either on its own or with an incision, relieves the pain and pressure. Fistulas are associated with drainage of blood, pus, or mucus, but they are generally not painful unless the pus builds up inside the tract.

Does an Abscess Always Become a Fistula?

No. A fistula develops in about 30-50 percent of all abscess cases, and there is really no way to predict if this will occur. If drainage persists for two to three months, the diagnosis of perianal fistula is made.

How Is an Abscess Treated?

An abscess is treated by draining the pus through an opening made in the skin near the anus. Often this can be done in the doctor's office using a local anesthetic. After the abscess is drained the surgeon may insert a small wick of gauze into the cavity of the abscess to allow it to continue to drain over the next several hours. Unless the infection is particularly severe, antibiotics are usually not necessary and may cause other complications, particularly diarrhea. A large or deep abscess may require drainage in the operating room. Hospitalization may be necessary for patients susceptible to more serious infections, such as diabetics or people with decreased immunity.  In these patients, antibiotics play an important role in the treatment.

Fairfax Colon Rectal Surgery’s Approach

The sooner the patient is seen after the onset of their symptoms the sooner the patient will begin to feel relief of their pain.  In addition, the longer the abscess is left untreated the larger it is likely to become and the greater the risk or additional complications.  At Fairfax Colon and Rectal Surgery we make every effort to promptly see you within 24 hours of your call so that you can be relieved of this problem as quickly as possible.  If you suspect you have a anal abscess, we recommend you call the office and tell the receptionist that you are in acute pain.  If at all possible you will be seen that day for treatment.

After Treatment

Symptoms and Care

There will be some pain after the local anesthetic wears off. It may be moderately strong but not nearly what it was prior to the drainage procedure. Your doctor will prescribe something for you. Do not take aspirin or products containing aspirin for at least seven days as they promote bleeding. You may take acetaminophen (Tylenol®) or ibuprofen.

It takes two to four weeks for the wound to heal. Don't worry if some bleeding, discharge, pus, or itching occur during this time; they are part of the normal healing process. You may apply gauze, cotton dressings, or minipads to the wound as needed.

Anal hygiene is important. Take a bath or shower once or twice a day for the next few days. (A hand-held sprayer is helpful if you are taking a shower.) Bowel movements will not cause any further infection, but wash the skin with water after movements.

The patient will be asked to return to the office in 7 to 14 days for a check-up. Most patients with perianal abscesses will need no further treatment. If you develop a chronic fistula, surgery may be necessary.


It is important to keep your bowel movements soft and regular. Eat foods high in fiber and drink lots of water (6-8 glasses a day). If you are constipated, take a fiber supplement like Metamucil® or Konsyl®. Prune juice or small doses of milk of magnesia may also be used.


Avoid strenuous activity for the rest of the day. Tomorrow you can go back to your normal activities.

Causes for Concern

Call your doctor if you have any of the following problems:

  • Excessive pain unrelieved by your pain medication
  • Increasing pain several days after treatment
  • Fever or chills
  • Difficulty urinating
  • Severe bleeding that won't stop with direct pressure using Kleenex or gauze
  • Severe constipation (no bowel movement for three days)
  • Diarrhea (more than three watery bowel movements within 24 hours)
  • Nausea or vomiting

If your own doctor is unavailable, the doctor on call is available 24 hours a day, every day of the year. After hours, call any of our offices and the answering service will locate one of our doctors on call. In an emergency try to contact us for advice before you go to the hospital. A telephone call may save you a lot of time, discomfort, and expense.

How Is a Fistula Treated?

Surgery is generally necessary to treat a perianal fistula. This usually 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 surgery can be performed on an outpatient basis in our Ambulatory Surgery Center. If the fistula involves too much sphincter muscle, a two-stage procedure or more complicated repair may be necessary.

What Can I Expect After Fistula Surgery?

Discomfort after fistula surgery can be mild to moderate for the first week and can be controlled with pain pills. The amount of time lost from work or school is usually minimal. There will be no limitation 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 or minipad to prevent the drainage from soiling your clothes. Bowel movements will not affect healing.

Will an Abscess or Fistula Recur?

If proper healing occurs, the problem usually will not return. If your bowels are otherwise normal, you are probably not at higher risk for developing another abscess.

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