A superficial abscess is called a perianal abscess. It is usually a red painful swelling around the anal opening. 

A deep abscess or perirectal abscess could be the cause of very severe pain in the anal or pelvic area, but may not be visible during a routine external examination. 

These deep abscesses, because of their location, are usually diagnosed late, and may be the source of complications such as gangrene or sepsis diffused to the whole body, especially in diabetics or in patients with disorders of the immune system. 

Sometimes a perianal or perirectal abscess, may result in a fistula, which is a communication between the inside of the rectum and the skin.

If the abscess causes damage to the sphincter muscle or causes too much scarring, incontinence may result. 

The gold standard treatment of a perianal abscess is surgical drainage of the pus as soon as possible. 

Antibiotics often are not needed and sometimes they may be counter-productive because they may delay the diagnosis and the proper treatment.