Complex transsphincteric ano-rectal fistula with circumferential perirectal abscess and periprostatic extension: the added value of contrast-enhanced pelvic MRI

Complex perianal fistulas can harbor extensive secondary extensions and pelvic sepsis despite minimal systemic symptoms and normal inflammatory markers, creating a high risk of incomplete surgery when anatomy is underestimated. We report a case of a complex transsphincteric fistula (Parks classification) with suspected supralevator involvement in which preoperative MRI provided decisive anatomic mapping for operative planning. Multiplanar T2-weighted imaging delineated the primary tract, its relationship to the sphincter complex and levator plate, and extension into the ischioanal/ischiorectal fossae, while also demonstrating features consistent with secondary tracts and occult abscesses—findings that commonly explain postoperative persistence or recurrence if missed. Notably, gadolinium-enhanced fat-suppressed T1-weighted sequences increased conspicuity of subtle distal rectal communications that were poorly visualized on T2-weighted images, supporting the utility of contrast in selected scenarios to distinguish enhancing active tracts/abscess walls from surrounding inflammatory oedema or fibrosis. Given concomitant distal rectal ulceration on endoscopy, an inflammatory bowel disease work-up was considered to exclude fistulizing Crohn’s disease, for which careful staging of perianal sepsis and combined medical–surgical management are recommended. This case highlights the value of MRI (including contrast-enhanced protocols when indicated) as a preoperative adjunct to examination under anaesthesia, enabling tailored, sphincter-preserving strategies and comprehensive sepsis control in complex fistulizing disease.