see also:

• ano-rectal pain
• perianal abscess

• deep abscesses adjacent to the rectum

• deep abscess within fat of ischiorectal fossa
• can track to opposite side to form a horseshoe-shaped track

• following injection of haemorrhoids

• lie between the two walls of the inner and outer anal sphincters
• extremely painful and may drain into either the rectum or outside the anus
• painful lump can usually be felt just inside the anus

• located above levator ani
• usually follows pelvic cellulitis but may occur as complication of inflammatory bowel disease (IBD), diverticulitis, rectal Ca but may follow upward extension of an ischio-rectal abscess
• much less common, but tend to present late