An anorectal abscess is a pocket of pus in the tissue near the end of the rectum (anus). Most abscesses are caused by a blocked anal gland that develops an infection.
Other possible causes of an anorectal abscess include:
- Infection in an anal fissure.
- Complications of diseases that affect the colon, such as Crohn's disease, inflammatory bowel disease, or diverticulitis.
- Sexually transmitted infections.
Symptoms of an anorectal abscess include:
- A painful swelling (mass) around the anus.
- Drainage of pus from the anus.
- Pain in or around the anus.
- Pain when passing stool.
A person should see a doctor if an anorectal abscess is suspected. Treatment is needed to prevent worsening of the infection and serious illness.