Rules for anal fistulas with scrotal extension

Objectives: To evaluate the rules for anal fistulas with scrotal extension, in particular, whether a high transsphincteric or suprasphincteric fistula, of which internal openings are usually located posteriorly, would extend into the scrotum. Methods: We retrospectively analyzed 446 consecutive male patients who underwent definitive anal fistula surgery. We compared fistulas with scrotal extension according to the location of the internal opening and divided them into anterior and posterior groups. Results: Forty-six (82.1%) of the 56 anal fistulas with scrotal extension had anterior internal openings. After excluding recurrent fistulas, 42 (87.5%) of the 48 anal fistulas with scrotal extension had anterior internal openings. The relative risk of scrotal extension in the anterior group was 14.22 times higher than that in the posterior group (95% CI: 7.43-27.21; p<0.0001). After excluding recurrent fistulas, this relative risk rose to 18.67 (95% CI: 8.18-42.58), (p<0.0001). Conclusions: Anal fistulas with scrotal extension are mostly low transsphincteric or intersphincteric with anterior internal openings. High transsphincteric or suprasphincteric fistulas rarely extend into the scrotum, except in recurrent cases

Analysis of Deep Posterior Anal Fistulas by Magnetic Resonance Imaging: Site of Primary Abscess and Extension Patterns According to the Primary Abscess Depth

Objectives: The aim of this study was to use magnetic resonance imaging (MRI) to elucidate the site and depth of the primary abscesses associated with deep posterior anal fistulas and their extension patterns. Methods: We analyzed 176 consecutive patients with deep posterior anal fistulas and classified the fistulas according to whether the MRI-detected site of the primary abscess was at a superficial or a deep external anal sphincter (EAS) level. Results: The distance between the anal center and the primary abscess center was significantly shorter than the length of the EAS and radius at an angle of 45°. In addition, deep posterior anal fistulas with primary abscesses located at the deep EAS level penetrated the EAS significantly more laterally and made external openings at a significantly more lateral site than when the primary abscess was located at a superficial EAS level. Conclusions: Primary abscesses associated with deep posterior anal fistulas are located in the posterior intersphincteric space or in the EAS muscle itself, not in Courtney's space, as had previously been claimed