Fig. 3
a, b MRI axial and coronal T2 WI showing fluid filled left low anterior intersphincteric fistulous tract with fibrotic wall seen breaching the internal anal sphincter at the level of the superficial part of the external sphincter opposite1 o'clock (red arrows). c, d Ultrasound axial images show hypoechoic fistulous tract seen within the left anterior intersphincteric space breaching the internal sphincter (internal opening) opposite 1 o'clock (yellow arrows). e Post reconstruction coronal ultrasound images show left hypoechoic low intersphincteric fistulous tract breaching the internal sphincter at the level of the superficial part of the external sphincter (blue arrow)