The Role of Magnetic Resonance Imaging in Preoperative Evaluation of Perianal Fistulas: A Cross-Sectional Study on Diagnostic Accuracy, Classification, and Surgical Implications

Introduction:Perianal fistulas (PF) present significant clinical challenges due to their complexity and risk of recurrence. This study aimed to evaluate the role of MRI in the preoperative detection and characterization of perianal fistulae. Materials and Methods: A prospective cross-sectional study was conducted at Teaching Hospital-Erbil city-Kurdistan region-Iraq (March 2022–February 2023) involving 59 patients with symptomatic PFs. All underwent preoperative MRI using a 1.5T scanner with T1-weighted, T2-weighted, STIR, and diffusion-weighted sequences. Two radiologists independently analyzed images for fistula type (Parks’ classification), secondary extensions, and sphincter involvement. Findings were compared to intraoperative results. Results: The most common locations of the internal fistula opening were left anterolateral 16 (24.6%) and left posterolateral 14 (21.5%). The abscess was separated in 10 (15.4%) and connected in 4 (6.2%) of the fistulae. The most common type among males was the inter-sphincteric 40 (87.0%) compared with 10 (52.6%) among females (P = 0.004). The most common type of fistulae among those with no secondary branch was the inter-sphincteric 41 (85.4%) compared with 9 (52.9%) among those with secondary branch (P = 0.011). The incidence rates of separated and connected abscesses were 6 (12%) and 1 (2%), respectively, among the inter-sphincteric fistulae (P = 0.007). Conclusion:The current study illustrates the significant role of MRI in the comprehensive preoperative evaluation of PFs. Given MRI's high accuracy in identifying fistula tracts, detecting secondary branches, associated abscesses, and determining the relationship of the fistula with the sphincter complex, improved surgical planning becomes possible.