Clinical Examination, Endosonography, and MR Imaging in Preoperative Assessment of Fistula in Ano: Comparison with Outcome-Based Reference Standard

Research Question/Objective Fistula in ano is a common condition with the tendency to recur despite seemingly curative surgery. Preoperative imaging can alert the surgeon to infection that would otherwise be missed. Magnetic resonance (MR) imaging can depict fistulas and any associated secondary tracts or abscesses. It allows physicians to identify features specifically associated with postoperative recurrence and could alter the surgical approach. The benefit of preoperative investigation of fistula in ano with use of anal endosonography remains uncertain. The central aim of this study was to prospectively evaluate the relative accuracy of digital examination, anal endosonography, and magnetic resonance (MR) imaging for preoperative assessment of fistula in ano by comparison with an outcome-derived reference standard.