Comparison of preoperative MRI and surgical findings in perianal fistulas and factors affecting recurrence

Abstract

Aims: Anal fistula occurs most commonly when the anal glands become obstructed and infected in the intersphincteric plane. Although it has a high recurrence rates, its treatment is surgical. Magnetic resonance imaging (MRI) is the gold standard for accurate preoperative evaluation of the patient and detection of the relationship to the muscle groups that provide continence. The aim of this study was to evaluate the compatibility of MRI with surgery and to determine the parameters effective on recurrence. Methods: Primary perianal fistulas with MRI between 2016 and 2023 were retrospectively evaluated. Patient demographics were documented. Fistula classifications according to MRI findings, abscess locations, internal and external opening regions on MRI were compared with surgical findings. The surgical procedures performed were documented. Univariate and multivariate evaluations of recurrence performed by Cox regression analysis. Disease-free survival data were analyzed. Results: A total of 180 cases with a mean age of 43.75±12.57 years were included in the study. At the end of MRI, there were 69 (38.3%) cases with an fistula external orifice > 3 cm. The largest group in Parks classification were intersphincteric patients with 127 (66.7%), 52 (28.9%) of the patients were in the complex group. The level of agreement between surgery and MRI internal opening was 13.4% and statistically significant (Kappa coefficient of agreement 0.134; p<0.01). Total recurrence was observed in 33(18.3%) patients. Recurrence was statistically significant in patients with external orifice >3 cm, transsphincteric, complex and patients requiring loose seton in surgery (p=0.001, p=0.001, p=0.001, p=0.001, p=0.007; p<0.01 respectively). Conclusion: In our study, we found that the recurrence rate was higher in patients with an external orifice of more than 3 cm, transsphincteric, 3-4th degree complex fistulas, and patients with loose setons.

Keywords

• Anal fistula
• magnetic resonance imaging
• recurrence
• classification

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