J Korean Soc Med Ultrasound.  1997 Dec;16(4):321-326.

The Usefulness of Endoanal Sonography in the EvaluEtion of Fistula-in-Ano

• Shin SS
• Jeong YY
• Kang HK
• Hwang EH
• Jeong TW
• Seo JJ
• Park JG

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.

MeSH Terms

Classification
Fistula
Humans
Mass Screening
Sensitivity and Specificity
Ultrasonography