Parks Classification (Anal Fistula)
Parks classification (Parks 1976) of an anal fistula (fistula-in-ano), by the tract's relationship to the anal sphincter complex - guides surgical planning and the continence risk.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Parks type
- Transsphincteric - through both sphincters
Result: Parks transsphincteric: the tract passes through both the internal and external sphincters into the ischioanal fossa.
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Intersphincteric
- Through the internal sphincter only, in the intersphincteric plane; the most common type.
- Transsphincteric
- Through both the internal and external sphincters into the ischioanal fossa.
- Suprasphincteric
- Above the puborectalis, then down through the ischioanal fossa; complex.
- Extrasphincteric
- Outside the sphincter complex, through the levator ani into the rectum; complex.
What you enter
- Parks type
How this is calculated
Parks AG, Gordon PH, Hardcastle JD. A classification of fistula-in-ano. Br J Surg. 1976;63(1):1-12. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.