An anal abscess is a painful condition in which a collection of pus develops near the anus. Most anal abscesses are a result of infection from small anal glands.
The most common type of abscess is a perianal abscess. This often appears as a painful boil-like swelling near the anus. It may be red in color and warm to the touch. Anal abscesses located in deeper tissue are less common and may be less visible.
Surgical incision and drainage is the most common treatment for all types of anal abscesses and is usually successful.
About 50% of patients with an anal abscess will develop a complication called a fistula. A fistula is a small tunnel that makes an abnormal connection between the site of the abscess and the skin.
In some cases, an anal fistula causes persistent drainage. In other cases, where the outside of the tunnel opening closes, the result may be recurrent anal abscesses. Surgery is needed to cure almost all anal fistulas.
Causes of Anal Abscesses
An anal abscess can have many different causes. These include:
- Infection of an anal fistula. An anal fistula is a small superficial tear in the skin of the anal canal.
- Sexually transmitted infections.
- Blocked anal glands.
Risk factors for anal abscesses include:
- Inflammatory bowel disease such as Crohn's disease or ulcerative colitis
- Pelvic inflammatory disease
- Being the receptive partner in anal sex
- Use of medications such as prednisone
For adults, using condoms during sexual intercourse, including anal intercourse, can help prevent anal abscesses. For infants and toddlers, frequent diaper changes and proper cleaning during diaper changes can help prevent anal fistulas and perianal abscesses.