Department of Diagnostic Radiology, Chonnam University Medical School, Korea.
Published online: January 1, 2001.
ABSTRACT
PURPOSE: To evaluate the role of pre-operative endoanal sonography in patients with fistula-in-ano MATERIALS AND METHODS: During the last one year, ninety patients with suspected fistula-in-ano were examined. For endoanal sonography, ultrasound scanter with a 7-MHz rotating probe was used to provide a 360 degrees image. Ultrasonographic images were interpreted by two radiologists, who were blinded to the operative findings, with regard to detection and classification of fistula-in-ano and detection of internal opening ; the final interpretation was obtained by concensus. Fistulae were classified into four types ; intersphincteric, transsphincteric, suprasphincteric, and extrasphincteric. RESULTS: Fistulous tracts were detected in 85 of 90 patients on operation. Of 85 patients with fistulous tracts, five had multiple fistulous tracts and overall 95 fistulous tracts were detected. On endoanal sonography, fistulous tract was detected in 85 of 95 fistulous tracts (sensitivity 89%, specificity 80%, accuracy 89%). With regard to classification of fistula-in-ano, sonographic and surgical findings were concordant in 77% (k=0.5503, moderate agreement). Internal opening was detected in 88 of 95 internal openings with endoanal sonography (sensitivity 93 %, specificity 80%, accuracy 92%). CONCLUSION: Endoanal sonography may be advocated as the initial screening modality in the evaluation of fistula-in-ano.