[Application of three-dimensional endoanal and endorectal ultrasound in the diagnosis of anorectal fistula].

Objective: To evaluate the efficacy of three-dimensional anal and endorectal ultrasound in identifying the internal opening and tracing the tract of the anorectal fistula.

Methods: From November 2008 to January 2010, 127 patients suffering anorectal fistula were managed with three-dimensional endoanal and endorectal ultrasound. The internal opening, the tract of the fistula and fistula trace were identified by the ultrasonography with three-dimensional imaging. All results were confirmed and compared with findings from the operation.

Results: The internal opening of the fistula was specified in 116 patients, the accuracy rate was 91.3% (116/127). The internal opening of the fistula was located above the dentate line in 112 patients, and located in rectal ampulla in 4 patients. The main fistula tract was identified in all the patients, the accuracy rate was 100%. In this group, the fistula tunneled as follows: trans-sphincteric in 47 patients, intersphincteric in 75 cases, supra sphincteric in 2 cases, extra sphincteric in 3 patients. Secondary extension was found in 37 patients, the accuracy rate was 100% (37/37).

Conclusions: Three-dimensional anal and endorectal ultrasound is an effective way for localizing the internal opening and the tract of anorectal fistula. It can provide valuable information for curative operation.