Perirectal Abscess



  • Abscess in the perirectal area
  • May be associated with fistula-in-ano
  • Classification of the abscess is based on the location in relation to the levator and sphincteric muscles of the pelvic floor.
  • Classification by decreasing frequency: perianal, ischioanal, intersphincteric, and supralevator


  • May occur at any age
  • More common in males 2:1
  • In children, more common in those <2 years


  • Most often originates from an occluded anal gland with subsequent bacterial overgrowth and abscess formation
  • Infection from within the anal glands, penetrates through the internal sphincter, and ends in the intersphincteric space
  • Chronic infection and inflammation may result in the formation of fistula-in-ano. This occurs in up to 50% as a result of persistent anal sepsis or an epithelialized tract.
  • Also can be associated with transmural inflammation and fistulization of the rectosigmoid mucosa due to Crohn disease


  • Nonspecific anal gland infection
  • Crohn disease
  • Immune deficiency (e.g., neutropenia, diabetes mellitus, AIDS)
  • Perforation by a foreign body
  • External trauma
  • Tuberculosis
  • Chronic granulomatous disease (CGD)
  • Tumor (e.g., carcinoma, rhabdomyosarcoma)

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