The Parks classification of anal fistulae defines which type as crossing the external sphincter at some level and passing through the ischiorectal fossa to open on the perianal skin?

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

Explanation

Parks classification: Intersphincteric — track passes between internal and external sphincters; Transsphincteric — track crosses the external sphincter into ischiorectal fossa (most common surgical challenge — ~25% of fistulae); Suprasphincteric — track goes above puborectalis through levator; Extrasphincteric — track completely outside both sphincters, communicates with pelvic structures. Transsphincteric fistulae require careful sphincter-preserving techniques (seton, LIFT procedure, or mucosal advancement flap) to avoid incontinence.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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