An anorectal abscess is a collection of pus in the area of the anus and rectum. Anal abscess; Rectal abscess; Perirectal abscess; Perianal abscess; Gland abscess; Abscess - anorectal Common causes of anorectal abscess include: Blocked glands in the anal area Infection of an anal fissure Sexually transmitted infection (STD) Trauma