Anal Abscess (and Anal Fistula)
(Anal Rectal Abscess, Anorectal Abscess; Anal Rectal Fistula, Anorectal Fistula)
An anal abscess is a puss-filled glandular cavity near the anus, either deep in the rectum or close to the anus opening. Eight-to-nine people out of 10,000 will experience an anal abscess.
Abscesses result when bacteria infect a mucus-secreting gland in the anus or rectum, causing blockage and damage to surrounding intramuscular tissue. The reason why the infection occurs in the first place is unknown because, normally, this area is free from infection.
A risk factor is something that increases your chance of getting a disease or condition.
The following factors increase your chance of developing an anal abscess. If you have any of these risk factors, discuss them with your doctor:
• Sex: Male
• Colitis or other inflammatory bowel disease
If you experience any of these symptoms do not assume it is due to an anal abscess. These symptoms may be caused by other health conditions. If you experience any one of them, discuss them with your doctor.
In the case of an abscess near the surface of the skin on the buttocks:
• Pain and tenderness radiating from the location of the abscess
• Visible redness and swelling
In the case of an abscess located deeper within the rectum:
• Pain in the lower abdomen
• Swelling in the rectum that can be seen during examination of the rectum
Anal abscesses may be accompanied by pain with stool and/or stool incontinence (inability to restrain stools)
Your doctor will ask about your symptoms and medical history, and perform a physical exam. While your doctor will be able to see an abscess near the surface of the skin, he or she may need to exam the rectum with a gloved finger to determine the presence of a deeper abscess.
Treatment normally consists of draining the abscess, which is done by making an incision through the skin near the anus into the abscess. For this, a patient is given local anesthesia. Rarely, a patient will need to be admitted to a hospital for this procedure and will be given general anesthesia. Antibiotics may be given to reduce fever or under other special circumstances.
Complications of Treatment
Following drainage (or natural rupture) of an abscess, more than half the cases will develop into anal fistulas —usually weeks but sometimes years later. In this condition, a permanent abnormal channel is formed from the site of the original abscess to the surface of the skin near the anus. This channel (fistula) allows for the continuous drainage of the abscesses’ puss-like fluid. In the case of a fistula, surgery to remove/close-up the channel is normally recommended. Following surgery, recurrence of a fistula is common, and stool incontinence problems may result.
There are no known ways to prevent anal abscesses or subsequent fistulas because the cause of the original infection of anal glands is unknown.