Treating highly complex anal fistula with a new method of combined intraoperative endoanal ultrasonography (IOEAUS) and transanal opening of intersphincteric space (TROPIS)

Introduction
Treatment of highly complex anal fistula is still a profound test for a specialist colorectal surgeon. The reasons are directly related to recurrence and incontinence.

Aim
To evaluate the clinical results of a combined method of intraoperative endoanal ultrasonography (IOEAUS) and transanal opening of the intersphincteric space (TROPIS).

Material and methods
This study retrospectively included 48 patients with complex anal fistula, all of whom underwent new surgical methods. This operation mainly consists of two steps. Firstly, the type of anal fistula was determined by endoanal ultrasonography (EAUS) or magnetic resonance imaging (MRI) before the operation. Then the TROPIS procedure was performed with the help of EAUS, and the decision on whether a drainage seton should be placed depended on the condition of the tract. If there were secondary tracts, they were found and the same was done.

Results
The median follow-up was 12 months. Two (4.1%) patients experienced recurrence. Four (8.3%) patients did not have primary healing. All 6 patients underwent the same procedure again, and three recovered completely. So total successful fistula healing was observed in 45 (93.7%). There were no major complications and no significant deterioration in anal function and incontinence postoperatively.

Conclusions
Combined IOEAUS and TROPIS is an effective procedure in the treatment of highly complex anal fistula, and it may offer a new means for other operations.