Diagnostic value of trans-fistula contrast-enhanced ultrasound in anal fistula

Abstract

Objective To assess the clinical value of trans-fistula contrast-enhanced ultrasound (CEUS) in diagnosing anal fistula. Methods An analysis was performed of 98 patients with anal fistula who underwent conventional ultrasound and trans-fistula CEUS from February 2016 to December 2017. We recorded the following parameters: fistulous trend and its positional relation with levator ani muscle and sphincter (Parks classification); the number of fistulous branches; the number of fistulas, the position of fistula, and the distance between fistulous internal opening and anal edge. Then, we compared these parameters with surgical diagnostic results. Results The accuracy of Parks classification performed by trans-fistula CEUS was significantly higher than that of conventional ultrasound (90.82% vs 80.61%, χ2=4.167, P=0.041). The accuracy of trans-fistula CEUS in the diagnosis of branch fistula was lower than that of conventional ultrasonography (81.08% vs 86.49%), but there was no significant difference (χ2=0.400, P>0.05). The accuracy of trans-fistula CEUS was significantly higher than that of conventional ultrasonography (92.68% vs 78.05%, χ2=10.543, P=0.001). Conclusion Trans-fistula CEUS has a high accuracy in the Parks classification and in the judgment of the internal orifice of anal fistula. It can make up for the deficiency of conventional ultrasonography and provide a basis for clinical treatment decision-making. Key words: Fistula; Contrast-enhanced ultrasound; Ultrasonography; Anal fistula