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

METHODSFrom 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.

RESULTSThe 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).

CONCLUSIONSThree-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.