An anal abscess, often referred to as a 'perianal abscess' ('perianal' means 'in the anal area'), is where a small cavity filled with pus forms in the anal area.
An infection in the anal area causes the buildup of pus. This is generally the result of a bacterial infection of small glands in the anal canal, the final section of the gastrointestinal tract, although if other conditions, especially inflammatory conditions of the bowel, are present, anal abscesses may occur more frequently.
The main symptom is the presence of a swelling near the anus, along with pain in that area, normally acute. There may also be a discharge of pus from the skin in the anal area or from the anus itself. Constipation, and/or pain when having a bowel motion are other common symptoms. Some anal abscesses can also cause fever and / or a general feeling of being ill.
A simple rectal examination is usually all that is needed to diagnose an anal abscess, although other tests may be recommended at the same time to check for the presence of other conditions such as bowel cancer, diverticular disease, inflammatory bowel disease or sexually transmitted infections.
Once an anal abscess is diagnosed, the standard treatment is a surgical procedure - 'surgical drainage' - to remove the pus. This is performed in hospital under general anaesthetic. The pain normally subsides when the pus has been drained away, as the pressure has been relieved. Further treatment may be required if an anal fistula is also present, which is not uncommon when an anal abscess has developed.