How can the assessment of fistula-in-ano be improved?

PURPOSE: Fistula-in-ano anatomy and its relationship with anal sphincters are\r\nimportant factors influencing the results of surgical management. Preoperative\r\ndefinition of fistulous track(s) and the internal opening play a primary role in\r\nminimizing iatrogenic damage to the sphincters and recurrence of the fistula.\r\nMETHODS: Physical examination and endoanal ultrasound (performed with a 10 MHz\r\nendoprobe), either conventionally or with an injection of hydrogen peroxide,\r\nwere performed in 26 consecutive patients. Results were matched with surgical\r\nfeatures to establish their accuracy in preoperative fistula-in-ano assessment.\r\nRESULTS: Accuracy rates of clinical examination endoanal ultrasound, and\r\nhydrogen peroxide-enhanced ultrasound were 65.4, 50, and 76.9 percent for\r\nprimary tracks, 73.1, 65.4, and 88.5 percent for secondary tracks, and 80.8,\r\n80.8, and 92.3 percent for horseshoe extensions, respectively. Compared with\r\nphysical examination and endoanal ultrasound, accuracy of hydrogen\r\nperoxide-enhanced ultrasound was higher for transsphincteric and\r\nintersphincteric primary tracks and horseshoe extensions. Both endoanal\r\nultrasound and hydrogen peroxide-enhanced ultrasound displayed a significantly\r\nhigher accuracy in detecting the internal openings (53.8 and 53.8 percent,\r\nrespectively) compared with clinical evaluation (23.1 percent; P = 0.027).\r\nCONCLUSIONS: Our data suggest that hydrogen peroxide-enhanced ultrasound can be\r\nvery reliable and useful in the definition of fistula anatomy, its relationship\r\nwith anal sphincters, and, hence, surgical strategy. It also improves\r\nidentification of secondary extensions, particularly horseshoe tracks. This\r\nmethod, besides being safe, economic and reputable, both preoperatively and\r\npostoperatively, could be helpful in checking operative results and recurrence.