To Evaluate The Re-Recurrence Outcome of Surgery in Cases of Recurrent Fistula in-Ano With Preoperative MRI Fistulogram: A Case-Control Study

Abstract Background: Recurrence rates after surgery on recurrent fistula-in-ano are higher than for surgery on index cases. Role of preoperative MRI fistulogram was evaluated in this study with respect to recurrence outcomes. Aim and objectives: Compare recurrence outcomes in patients who underwent surgery for recurrent fistula-in-ano with and without preoperative MRI. Material and methods: Study design is a case control study. Study population was all patients of Fistula-In-Ano who underwent Fistula-In-Ano surgery between May 2017 and Dec 2018. Case definition was those patients who underwent Fistula-In-Ano surgery with Preoperative MR Fistulogram between May 2017 to Dec 2018. Control definition was those patients who underwent Fistula-In-Ano surgery without MR Fistulogram prior to May 2017. Primary outcome variable was comparison of recurrence rates in patients with Recurrent Fistula in Ano. Data regarding cases were sourced prospectively whereas data regarding controls were sourced retrospectively from medical records and prospectively during OPD visits. Effect size was taken from previous study done by Buchanan et al who found reduction in recurrence rates upto 75% when surgery was guided by MRI in patients with recurrent Fistula-in- Ano. Results: In case cohort rates of recurrence increased among higher grade fistulas, ranging from 15.7% [Grade 3] to 33.3% [Grade 5] with a total of 15 recurrences. In the control arm Rates of recurrence increased among higher grade fistulas, ranging from 35.7% [Grade 3] to 60% [Grade 5] with a total of 34 recurrences. Analysis of recurrence rates in case arm showed 15 recurrences out of 75 cases [20%] whereas in control cohort there were 34 recurrences out of 75 controls [45.3%]. This was significant with P value of .001. Conclusion: The utility of MR Fistulogram is high in scenario of recurrent fistula in ano, owing to difficulty in identifying fistula tracts during EUA. Its value is increased especially in higher grade fistula-in-ano.