BACKGROUND: Perianal fistula refers to an abnormal connection between the anal canal and the perianal skin or perineum. Magnetic Resonance Imaging (MRI) plays a crucial role in accurately characterizing perianal fistulas, which informs surgical strategies and helps minimize recurrence.

METHODS: This cross-sectional study was conducted at a single diagnostic imaging center in Addis Ababa, utilizing retrospectively collected data from May 2023 to June 2024. All patients referred for suspected perianal fistulas were included. MRI scans were reviewed by a radiologist in body imaging fellowship and a body imaging subspecialist. Findings, along with sociodemographic data, were documented in a structured questionnaire and analyzed using SPSS.

RESULTS: The study encompassed 304 primary fistula tracts in 276 patients, with 233 (84.4%) being male. Complex fistulas were identified in 83 patients (30.1%), 43 (15.6%) had secondary extensions, and 64 (27.1%) presented with abscess collections. The most common type of fistula, according to the Parks classification, was intersphincteric, observed in 263 cases (86.5%). The St. James University Hospital grades 1 and 2 were predominant, representing 176 (57.9%) and 62 (20.4%) of the cases, respectively. A significant association was found between complex fistulas, higher Parks grades, and the total length of the fistula tract.

CONCLUSION: This study elucidates MRI patterns of perianal fistulas, revealing that over one-third of patients had complex fistulas. This underscores the importance of preoperative MRI for effective surgical planning and reducing recurrence rates.

KEYWORDS: Perianal fistula, MRI, recurrence, St. James Classification, Parks Classification