Gururaj Sharma1, Manjit Mohan2

Perianal fistulae though uncommon, can be quite distressing to the patient. Correct surgical management requires accurate pre-operative assessment and grading of this condition. MRI is now considered the modality of choice in the pre-operative assessment of perianal fistulae. We did a retrospective analysis of patients who underwent MR imaging for perianal fistulae in our institution, and compared it with the surgical findings. The purpose of the study was to evaluate the accuracy of MRI in the pre-operative grading of perianal fistulae. A total of 32 patients were included in this study. Of these, 12(37%) had type 1 intersphincteric, 8(25%) had type 2 intersphincteric, 6(18%) had type 3 transsphincteric, 4(12%) had type 4 transphincteric, and 2(6%) showed supra-levator extension. MRI was able to correctly grade the fistulous tract in 30 of these 32 patients, giving an accuracy of 94%. MRI was found to be extremely useful in the pre-operative assessment of perianal fistulae. It helps in correctly classifying the fistulae and to detect hidden or deep seated tracts or abscesses which would have been otherwise missed. Thus, it is useful in selecting the most appropriate surgical procedure, thereby reducing the chances of recurrence and to avoid complications such as fecal incontinence from occurring.