Intrarectal ultrasound in the evaluation of perirectal abscesses

Experience with intrarectal ultrasonography (IRUS) is limited for the evaluation of perianal sepsis. The purpose of this article is to report our experience with IRUS in evaluating 24 cases of suspected perianal abscess and fistula. IRUS was performed intraoperatively using a Brüel & Kjaer (Model #1846; Naerum, Denmark) endoanal ultrasound scanner with a 7-MHz transducer. After completion of the IRUS, careful anorectal examination and appropriate surgical therapy were performed. At surgery, 19/24 patients were found to have perirectal abscesses, with all 19 cases correctly identified preoperatively by IRUS. In 12 cases (63 percent), IRUS correctly defined the relationship between the abscesses and sphincters by Parks' classification. At surgery, internal openings of fistulous tracts were found in 14/19 cases, but IRUS identified only 4/14 (28 percent). In 6/24 cases, IRUS and clinical evaluation did not demonstrate a perirectal abscess. The role of IRUS in the evaluation of perirectal abscess is evolving. Certainly, uncomplicated abscesses can be managed without ultrasonography. However, IRUS can be an adjunct to careful evaluation of complex perianal suppurative disease.