MRI of a patient with recurrent perianal sepsis demonstrates a fistulous tract that passes above the puborectalis, crossing the levator plate to reach the ischiorectal fossa, with the internal opening at the posterior midline crypt. Which Parks classification category does this fit?

• A Intersphincteric fistula
• B Transsphincteric fistula
• C Extrasphincteric fistula
• D Suprasphincteric fistula ✓

Explanation

A suprasphincteric fistula tracks upwards in the intersphincteric plane over the top of the puborectalis, then pierces the levator ani to descend through the ischiorectal fossa. An extrasphincteric fistula bypasses the sphincter complex entirely, entering the rectum above the levator without traversing it, which distinguishes option C. Transsphincteric tracts cross both sphincters below the puborectalis, the commonest type seen surgically.

Reference: Bailey and Love's Short Practice of Surgery, 28th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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