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  • • Result from occlusion of anal glands and crypts at the dentate line

    • Occlusion may follow impaction of vegetable matter or edema from trauma

    • Abscesses are classified according to space they invade

    • -Supralevator





    • May also develop as a result of inflammatory bowel disease (Crohn)

    • Fistula-in-ano from the anus to the perianal skin develops when abscess cavity maintains persistent communication with the crypt

    Goodsall rule: Used to identify direction of fistula tract

    • -Anterior external opening: Tract extends in a radial direction to the dentate line

      -Posterior external opening: Fistula tract curves to the posterior midline


  • • 10% of patients with Crohn disease have anorectal abscess fistulous disease with no prior history of inflammatory bowel disease

Symptoms and Signs

  • • Severe anal/perianal pain, usually continuous and throbbing

    • Pain may worsen with movement and straining

    • Swelling and discharge may be noted

    • Patients may have fever, urinary retention

    • Severe, life-threatening perineal sepsis may develop

    • Patients with fistula-in-ano may have pain and bloody discharge

    • Exam findings may include tender perianal or rectal mass

    Fistula: Internal and external openings with mucopurulent drainage

    • Fistulous tract is often palpable and firm

Laboratory Findings

  • • May have elevated WBC count, especially with perineal sepsis

    • Drainage may have white blood cells, bacteria

Imaging Findings

  • • Imaging studies are unnecessary in uncomplicated cases

    • Sinogram may reveal fistulous tract and branches

    • Transrectal US may reveal extent of sphincter involvement

    • CT scan may be helpful in identifying supralevator abscesses

  • • Inflammatory bowel disease (Crohn disease)

    • Pilonidal disease

    • Hidradenitis suppurativa

    • Anal tuberculosis

    • Actinomycosis

    • Trauma

    • Anal fissure

    • Anal malignancy

    • Radiation injury

    • Chlamydiosis

    • Diverticulitis

    • Retrorectal tumors

Rule Out

  • • Crohn disease

    • Anorectal malignancy

  • • History and physical exam

    • -Is there history of diabetes or immunocompromised conditions, including medications (steroids, chemotherapy)?

    • Imaging studies are not indicated for uncomplicated cases

When to Admit

  • • Abscesses should be drained; admission will depend on extent of abscess drainage required

    • Signs of perineal sepsis or complicated abscess

    • Fistula-in-ano by itself is not a surgical emergency

  • • Treatment for abscess is surgical drainage

    • Intersphincteric abscesses are treated with internal sphincterotomy

    • Perianal and ischiorectal abscesses are drained through the perianal skin

    Fistula-in-ano: Fistulotomy, currette tract and granulation tissue, heal by secondary intention

    Fistula-in-ano: Involving external sphincter may be treated with seton placement or drainage with delayed repair with an endorectal advancement flap



  • • Anorectal abscesses require surgical drainage

    • Patients with diabetes or immunocompromised require urgent ...

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