Step 1: Understanding the Question:
Park’s classification is the standard system for categorizing fistulae-in-ano based on their relationship to the internal and external anal sphincters. Step 2: Detailed Explanation:
Intersphincteric Fistula (Option A): This is the most common type (approx. 45-70%). The tract runs between the internal and external sphincters in the intersphincteric plane and opens on the perianal skin. It does not cross the external sphincter.
Transsphincteric Fistula: The tract passes from the intersphincteric plane through the external sphincter into the ischiorectal fossa.
Suprasphincteric Fistula: The tract passes upwards in the intersphincteric plane, goes over the top of the puborectalis muscle, and then descends into the ischiorectal fossa to the skin.
Extrasphincteric Fistula: This is the rarest type. The tract runs from the rectal lumen (above the levator ani) directly through the levator muscles to the skin, bypassing the sphincter complex entirely.
Significance: Identifying the type of fistula is crucial for surgery. Intersphincteric fistulae can usually be treated by a simple fistulotomy, whereas higher types may require a seton or more complex repair to avoid incontinence.
Step 3: Final Answer:
The fistula tract shown passing only between the two sphincter layers is classified as Intersphincteric.
