Evaluation of perianal sepsis: Comparison of anal endosonography and magnetic resonance imaging

Abstract

The purpose of this study was to compare prospectively the diagnostic yield of anal endosonography (AES) and magnetic resonance imaging (MRI) in the assessment of perianal fistulae and abscesses. There were 39 patients (14 men, 25 women; mean age, 40 years) who underwent AES, performed with a 10-MHz rotating endoanal probe and MRI at 1.0 T (axial and coronal T2-weighted turbo spin-echo (TSE) and turbo-STIR sequences). Fistulae were classified as subcutaneous, intersphincteric, transsphincteric, high (i.e., high extrasphincteric or suprasphincteric), rectovaginal, and horseshoe and were compared with the surgical findings in all patients. Overall, 58 fistulae (subcutaneous, N ‫؍‬ 7; intersphincteric, N ‫؍‬ 9; transsphincteric, N ‫؍‬ 16; high, N ‫؍‬ 17; rectovaginal, N ‫؍‬ 5; and horseshoe, N ‫؍‬ 4) were detected at surgery. MRI showed a sensitivity of 84% and AES of 60% (P < .05). False-positive diagnoses were made in 6 patients (15%) with MRI and in 15 patients (26%) with AES, for a specificity of 68% and 21%, respectively (P < .05). Our findings show that MRI is superior to AES in the assessment of fistula-in-ano before major surgery. AES should be used only for orientation before minor procedures, such as incision or drainage of subcutaneous fistulae.

Role of Different Diagnostic Modalities In Bhagandara I.E. FistulaIn-Ano

“…Fistulogram is more accurate in giving information regarding the number of internal openings and the length of the fistulous tract whereas MR Imaging is more successful in revealing the types and the sub types of fistula, the extensions of fistula and the connections of the tract with the surrounding structures. These findings are in agreement with most of the comparative studies between MRI and other imaging studies like endoanal sonography agreed that MRI is significantly superior 10 . From the overall study it has become very clear that both the diagnostic modalities have some merits over the others but at the same time each modality has its own demerits also.…”

“…MR imaging has emerged as the leading contender for preoperative classification of fistula in ano. It help to accurately classify tracts and also identify disease that otherwise would have been missed and had a palpable effect on surgical treatment and patient outcome 10 . Bhagandara is a cumbersome disease, it takes long duration to heal and it is very difficult to cure 11 .…”

Role of MRI Fistulography with Gadopentate Enhancement in Assessment of Complex Anal Fistulas and Improving Surgical Outcomes

“…The advent of three dimensional technology made ERUS a more accurate and reproducible tool in determining the type and height of anal fistulae as reported in a recent study [12]. Although ERUS can effectively assess some types of complex FIA, MRI is generally deemed superior for the appraisal of more complex anal fistulas [21]. The key advantages of MRI include being well tolerated without the need for previous preparation [19], the high spatial resolution of the image, and possibility of multiplanar imaging [22].…”

“…T2-Weighted image sequence was applied with the use of intravenous infusion of gadopentat emeglumine as a contrast medium. The vast majority (93.6%) of FIA had a high grade (3)(4)(5) according to the MRI-based grading which correlates with less favorable outcomes [24]; this may explain the relatively high rate of FI postoperatively.…”

“…Moreover, failure to appreciate complex ramifications of FIA can result in recurrent sepsis [3,4]. Missing secondary tract extensions at surgery is usually the principal cause of recurrence, hence adequate surgery is mandatory in more extensive disease [5].…”