A Diagnostic Approach to a Rare Case of a Recto-Cutaneous Fistula Following Recurrent Perianal Abscess: A Case Report

Background: Perianal abscess is caused by an infection of anal glands located in between the sphincter muscles of the anal canal. An enterocutaneous fistula is a chronic manifestation of an acute perirectal process that forms an anal abscess. The rate of perianal abscess is increasing annually and the incidence of fistula formation following perianal abscess occur reportedly at a higher rate. Precise diagnosis of a recto-cutaneous fistula is a key factor in its eventual management. This article discusses a diagnostic approach to a rare case of a recto-cutaneous fistula using magnetic resonance imaging (MRI). Case Report: A 24-year-old male presented with a 3 x 3 cm right buttock lesion of 5 months' duration. The wound had a scanty whitish discharge and flatus passage. He had been diagnosed with perianal abscess twice before, for which incision and drainage was done. The problem did not resolve and he had an additional, yet futile, explorative surgery. Physical examination revealed an opening on right buttock with spontaneous purulent discharge. Laboratory analysis of fluid specimen yielded no active bacterial growth. The patient had prolonged antibiotic treatment with no improvement. Pelvic MRI identified a long and deep fistulous tract extending from the right gluteal region into the muscular plane of the gluteus, invading the pubo-rectalis muscle and above levator ani muscle deep into the rectum, compatible with a recto-cutaneous fistula. Conclusion: Although rare, recto-cutaneous fistula should be diagnosed as early as possible to avoid long-lasting complications. There are several examinations to diagnose perianal fistula and MRI is of particular interest in assessment of fistula depth, route and extension given its high diagnostic accuracy. This report can aid surgeons in making accurate surgical plans pre-operatively and minimizing ham caused by surgery to patients.