This composite figure illustrates a human intersphincteric perianal fistula using two imaging modalities. Image (a) is a conventional radiographic fistulogram showing a thin, contrast-filled tract near the midline with an internal communication point within the anal canal. Images (b), (c), and (d) are sequential posterior-to-anterior coronal fat-saturated T2-weighted MRI scans. These images demonstrate the anatomy of the anal sphincter complex where the external anal sphincter appears as a hypointense (dark) lateral structure and the internal sphincter/mucosa is relatively hyperintense. A small, high-signal intensity (bright) tract is clearly visible within the intersphincteric plane, located medially to the right external sphincter. The sequence captures the fistula's course as it originates in the intersphincteric space and eventually opens into the anal canal (arrow in d). The fat-saturated MRI technique provides excellent contrast between the fluid-filled inflammatory tract and the surrounding muscular structures and suppressed ischioanal fossa fat, which is essential for accurate surgical planning and classification of perianal fistulous disease.

This diagnostic image is an axial MRI scan of the male pelvis, specifically a dedicated fistula protocol study with intravenous contrast. The image highlights the perianal region and pelvic floor anatomy. Anatomical landmarks include the gluteal muscles, pelvic bones, and the anal canal. Red arrows indicate bilateral, hyperintense linear tracts representing intersphincteric perianal fistulas. These tracts are situated within the intersphincteric space between the internal and external anal sphincters, with internal openings visualized at approximately the 5 o'clock and 7 o'clock positions. The rectum and sigmoid colon show evidence of mild circumferential wall thickening, suggesting an underlying inflammatory process. The surrounding soft tissues show subtle signal changes consistent with inflammation but lack evidence of complex trans-sphincteric extension, supralevator involvement, or localized abscess formation. This imaging is clinically significant for the classification of perianal Crohn's disease or chronic inflammatory conditions like Schistosomiasis-related granulomatous colitis, facilitating surgical planning and disease staging.

This composite educational image demonstrates the radiological assessment of perianal anatomy and fistula measurement using MRI. Panel A shows an unlabeled coronal T2-weighted MRI sequence of the perianal region. Panel B provides a color-coded anatomical overlay on the same MRI: the fistula tract is highlighted in green, the internal anal sphincter in yellow, the external anal sphincter (EAS) in red, the puborectal muscle in purple, and the levator ani in orange. The bottom schematic diagram (Panels C and D) illustrates the methodology for quantitative measurement. Label C indicates the vertical length or height of the external anal sphincter, while Label D represents the level of fistula penetration, defined as the vertical distance to the most cranial aspect of the tract penetrating the EAS or puborectal muscle. This resource is designed for radiologists and colorectal surgeons to standardize the classification and reporting of complex perianal fistulas.

Clinical photograph showing an intraoperative view of a fistulotomy for the treatment of an anal fistula. The image demonstrates a localized surgical field in the perianal region, surrounded by green sterile drapes and white gauze with visible serosanguinous fluid. A surgeon, wearing white sterile gloves, is utilizing a blue-handled electrocautery device to incise the fistula tract. Metallic surgical forceps are used to retract and stabilize the pinkish-red tissue, providing better visualization of the track being laid open. This procedural image illustrates the surgical principle of laying open a fistula-in-ano to allow for secondary intention healing. Key elements include the visualization of surgical instrumentation, anatomical exposure in colorectal surgery, and the use of thermal energy for tissue dissection and hemostasis.

This clinical photograph captures an intraoperative view of a surgical procedure to treat an anal fistula, likely an 'anal fistula-fistulotomy' or 'fistulectomy.' The patient is in the lithotomy position, and the surgical field is the perianal region. An encircling incision has been made around the external opening of the fistula. The image shows the meticulous dissection of the fistula tract from the surrounding subcutaneous tissue and muscle. A metal probe is visible, having been inserted through the tract to identify the internal opening within the anal canal. Surgical instruments, including a Langenbeck or similar retractor, are positioned to provide exposure, while hemostatic forceps (hemostats) are used to grasp and elevate the fibrous fistula tract. The tissue within the dissection site appears erythematous and raw, contrasting with the surrounding hyperpigmented perianal skin. Sterile blue drapes and clear plastic adhesive drapes are applied to maintain a sterile field. This visual serves as an educational example of the surgical approach to identifying and isolating a complex anal fistula tract while attempting to preserve the integrity of the anal sphincter muscles.

A clinical photograph captures an intraoperative view of a perineal fistulotomy, a surgical procedure performed to repair a low rectovaginal fistula by converting it into a third-degree tear for layered closure. The surgical field is framed by green drapes, exposing the perineal region with the patient in a lithotomy position. Visible tissue includes the vaginal mucosa, rectal mucosa, and dissected remnants of the perineal body. Active surgical intervention is depicted: a monopolar electrosurgical diathermy pencil with a blue tip is being used for hemostasis or tissue dissection along the incision line, while a surgeon's gloved hand manages suture material, likely 2.0 polyglactin (Vicryl). A white suture is seen held taut across the wound, which is undergoing anatomical reconstruction. The photograph illustrates the surgical approach of laying open the fistula tract, which involves dividing the bridge of skin, scar tissue, and anal sphincter muscle to facilitate a comprehensive, symmetric repair of the rectal muscle, internal sphincter, and vaginal wall.