An anal abscess is an infected cavity filled with pus found near the anus (the opening of the anal canal) or rectum (the portion of large intestine just proximal to the anal canal). This can results from a blockage of the anal glands located just inside the anus.
An abscess produces pain and swelling near the anal opening. Fever may also be present. Treatment consists of surgically draining pus from the infected cavity and making an opening (incision) in the skin near the anus to relieve pressure. Sometimes a small catheter is left in the incision for several days to assure adequate drainage. In the majority of individuals, a fistula will form after the abscess has been drained.

Anal Fistula (Fistula-In-Ano)

Anal Fistula is an abnormal passage (communication) between the interior of the anal canal or rectum and the skin surface. Rarer forms may communicate with the vagina or other pelvic structures, including the bowel.
Most fistulas begin as anorectal abscesses. When the abscess opens spontaneously (or has been opened surgically), a fistula may occur. Other causes of fistulas include tuberculosis, cancer, and inflammatory bowel disease. Fistulas may occur singly or in multiples.
Symptoms are usually a purulent discharge and drainage of pus and/or stool near the anus, which can irritate the outer tissues causing itching and discomfort. Pain occurs when fistulas become blocked and abscesses recur. Flatus (gas) may also escape from the fistulous tract. A fistula-in-ano is diagnosed when a probe has been passed between the opening on the skin’s surface and the interior opening.

Symptoms

Symptoms of both ailments include constant pain, sometimes accompanied by swelling, that is not necessarily related to bowel movements. Other symptoms include irritation of skin around the anus, drainage of pus (which often relieves the pain), fever, and feeling poorly in general.
A fistula develops in about 50 percent of all abscess cases and there is really no way to predict if this will occur.

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    Treatment

    An abscess is treated by draining the pus from the infected cavity, making an opening in the skin near the anus to relieve the pressure. Often, this can be done in the doctors office using a local anesthetic. A large or deep abscess may require hospitalization and use of a different anesthetic method. Hospitalization may also be necessary for patients prone to more serious infections, such as diabetics or people with decreased immunity. Antibiotics are not usually an alternative to draining the pus because antibiotics are carried by the blood stream and do not penetrate the fluid within an abscess.
    Surgery is necessary to cure an anal fistula. Although fistula surgery is usually relatively straightforward, the potential for complication still exists and should be performed by a specialist in colon and rectal surgery. It may be performed at the same time as the abscess surgery, although fistulae often develop four to six weeks after an abscess is drained sometimes even months or years later. Fistula surgery usually involves cutting a small portion of the anal sphincter muscle to open the tunnel, joining the external and internal opening and converting the tunnel into a groove that will then heal from within. Most of the time, fistula surgery can be performed on an outpatient basis – or with a short hospital stay.
    There is a direct relationship between incontinence and the amount of sphincter muscle divided. The goal of surgical treatment is thus two fold- to eradicate the suppurative process permanently without compromising anal continence.
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    Recovery

    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.
    Treatment of an abscess or fistula is followed by a period of time at home, when soaking the affected area in warm water (sitz bath) is recommended three or four times a day. Stool softeners may also be recommended. It may be necessary to wear a gauze pad or mini-pad to prevent the drainage from soiling clothes. Bowel movements will not affect healing.