Significance of MR imaging in setting the ball path of surgical management in perianal fistulae

ObjectiveTo study the role of magnetic resonance imaging (MRI) in surgical management of perianal fistulae.Materials and methodsThis study comprises of 30 patients: 19 with complex and 11 with recurrent perianal fistulae. Each had a DRE and pelvic MRI examination, and the imaging features were correlated with intraoperative findings. Since the position of internal opening, class of fistula and presence of secondary ramifications and/or abscess dictate the surgical management and its success, special attention was paid to these characteristics during MR imaging. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) both for DRE and MR imaging were calculated with respect to these characteristics with intraoperative data as gold standard.ResultsThe sensitivity of DRE in detection of internal opening was 33.33%, and of MRI 96.67%. DRE could classify the disease accurately in 33.33%, whereas MRI was able to do so in 86.67%. DRE could detect horseshoeing in 63.63% with a NPV of 82.60%, while MRI carried a sensitivity and specificity of 100%.ConclusionThe biggest Achilles heel in perianal fistulae surgery is the risk of recurrence. Since MR imaging identify the internal fistulous opening, classify the fistulae, and delineate the secondary tracts and extensions with a high degree of sensitivity and specificity, a preoperative MRI study can be extremely useful in charting the ball path of surgical management in complex and recurrent perianal fistulae. Forewarned of possible complicating factors, surgeon can plan the surgery well, and achieve a complete eradication of the disease.