Right trans-sphincteric perianal fistula starts at right perianal cutaneous opening and extends within the right ischio-anal and ischiorectal fossae. it then pierces the external anal sphincter opposite 10 o'clock to connect with horse-shaped tract within the inter-sphincteric plane. It ends by piercing the internal anal sphincter opposite 6 o'clock.
The fistula is filled with fluid signal and shows thick hypointense signal. Edema and smudging of the right ischiorectal fat planes around the aforementioned collection is noted. No abscess, or extension cranial to the levator ani.
No associated secondary tracts within the ischiorectal or ischioanal fossae.