Park classification of perianal fistulas

Park et al described perianal fistulas in the coronal plane according to course of fistula and relation to internal and external sphincters.

This was based on surgical findings of 400 patients referred to St Mark’s Hospital surgery in London, England.


  1. Intersphincteric
  2. Transsphincteric
  3. Suprasphincteric
  4. Extrasphincteric

Key inferences

  • External sphincter is the key landmark for this classification
  • 45% of the study were intersphincteric fistulas, the most common type encountered.
  • Next most common type was the transsphincteric group (30%)

Read more

  1. Parks, A. G., P. H. Gordon, and J. D. Hardcastle. “A classification of fistula‐in‐ano.” British Journal of Surgery 63.1 (1976): 1-12.
  2. de Miguel Criado, Jaime, et al. “MR imaging evaluation of perianal fistulas: spectrum of imaging features.” Radiographics 32.1 (2011): 175-194.
  3. Morris, John, John A. Spencer, and N. Simon Ambrose. “MR imaging classification of perianal fistulas and its implications for patient management 1.” Radiographics 20.3 (2000): 623-635.