What are the types of anal fistulas?

Updated: Nov 09, 2018
  • Author: Bruce M Lo, MD, MBA, CPE, RDMS, FACEP, FAAEM, FACHE; Chief Editor: Barry E Brenner, MD, PhD, FACEP  more...
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Anal fistulas are classified into the following 4 general types:

  • Intersphincteric - Through the dentate line to the anal verge, tracking along the intersphincteric plane, ending in the perianal skin

  • Transsphincteric - Through the external sphincter into the ischiorectal fossa, encompassing a portion of the internal and external sphincter, ending in the skin overlying buttocks

  • Suprasphincteric - Through the anal crypt and encircling the entire sphincter, ending in the ischiorectal fossa

  • Extrasphincteric - Starting high in the anal canal, encompassing the entire sphincter and ending in the skin overlying the buttocks

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