DefinitionAn anorectal abscess is a collection of pus in the area of the anus and rectum.Alternative NamesAnal abscess; Rectal abscess; Abscess - anorectalCauses, incidence, and risk factorsCommon causes include:Blocked gland in the areaInfection of an anal fissureSexually transmitted infectionDeep rectal abscesses may be caused by intestinal disorders such as Crohn's diseaseor diverticulitis.The following factors increase your risk for an anorectal abscess:Anal sexDiabetesInflammatory bowel disease (Crohn's disease and ulcerative colitis)Weakened immune systemThe condition may occur in infants and toddlers who are still in diapers and who have a history of anal fissures.SymptomsConstipation(may occur)Discharge of pus from the rectumFeverLump or nodule, swollen, red, tender at edge of anus