Abstract

Background: Accurate and comprehensive preoperative assessment of complex anal fistula classification is an important strategy to improve the success rate of surgery. Magnetic resonance imaging (MRI) is considered the imaging modality of choice for the evaluation and classification of fistula. The aim of this study was to assess the characteristics of complex anal fistula according to the St James classification based on magnetic resonance imaging.

Methods: A cross-sectional descriptive study was conducted on 51 patients with complex anal fistula according to St James classification who underwent MRI at Hue Central Hospital from March 2023 to October 2024.

Results: A total of 51 patients (including 90,2% men and 9,8% women) with a mean age of 42,0 ± 10,7 years were included in this study. Recurrent fistula included 20 cases (39.2%). Of the 51 complicated fistulas, 31.4% were grade 3, 62.7% were grade 4, and 5.9% were grade 5. A total of 55 primary fistulas, 55 internal orifice and 43 external orifice were recorded. 15 cases with secondary fistulas (29.4%) and 29 cases with associated abscesses (56.9%) were identified. There were 5.9% of cases with 2 secondary fistulas and 9.8% of cases with 2 abscesses.

Conclusion: Magnetic resonance imaging is a valuable imaging method in diagnosing and classifying complex anal fistula according to St James classification.