Abe Tatsuya, Tanaka Yoshiaki, Kunimoto Masao, Hachiro Yoshikazu, Ota Shigenori, Watanabe Kenji, Ohara Kei, Saitoh Yusuke, Murakami Masanori
Department of Proctology, Kunimoto Hospital, Asahikawa, Japan.
Department of Proctology, Terada Hospital, Tokyo, Japan.
J Anus Rectum Colon. 2025 Apr 25;9(2):244-251. doi: 10.23922/jarc.2024-086. eCollection 2025.
The Sumikoshi classification for anal fistulas is widely used in Japan; however, it does not include a category for transsphincteric fistulas. Therefore, low transsphincteric fistulas were included in type IIL (low intersphincteric) for convenience; however, high transsphincteric fistulas have not been properly classified. We defined high transsphincteric fistulas as type IIT and investigated their prevalence and clinical characteristics.
Consecutive patients who underwent fistula surgery at our hospital were included. The operative and endoanal ultrasonography records were retrospectively reviewed, and the following cases were reclassified as type IIT: cases documented as transsphincteric fistulas or cases with written records and/or illustrations indicating that the fistula tract penetrated the upper two-thirds of the external anal sphincter.
Of the 1,069 eligible patients, 895 (83.7%) had type II (intersphincteric) fistulas. Among the type II subtypes, type IIL was the most common with 771 (86.1%) patients, whereas type IIT accounted for 54 (6.0%) patients. The direction of the primary opening was more posterior (62.2%) in patients with type II fistulas other than type IIT, but it was more anterolateral (55.6%) in patients with type IIT fistulas. Patients with type IIT fistulas were more likely to undergo sphincter-sparing surgery than patients with other type II fistulas (37.0 vs. 3.7%, p<0.001).
Type IIT is not rare (6.0%) and should be treated as a complex fistula because of the greater involvement of the external anal sphincter. Surgeons may benefit by including type IIT as a new type II subclass in the Sumikoshi classification system.
Sumikoshi肛瘘分类法在日本广泛应用；然而，该分类法未包含经括约肌肛瘘这一类别。因此，为方便起见，低位经括约肌肛瘘被归入IIL型（低位括约肌间型）；然而，高位经括约肌肛瘘尚未得到恰当分类。我们将高位经括约肌肛瘘定义为IIT型，并对其患病率及临床特征进行了调查。
纳入在我院接受肛瘘手术的连续患者。对手术及肛门内超声检查记录进行回顾性分析，以下病例被重新分类为IIT型：记录为经括约肌肛瘘的病例，或有书面记录和/或图示表明瘘管穿过肛门外括约肌上三分之二的病例。
在1069例符合条件的患者中，895例（83.7%）为II型（括约肌间型）肛瘘。在II型亚类中，IIL型最为常见，有771例（86.1%）患者，而IIT型占54例（6.0%）患者。除IIT型外的II型肛瘘患者，其原发开口方向更偏后（62.2%），但IIT型肛瘘患者的原发开口方向更偏前外侧（55.6%）。与其他II型肛瘘患者相比，IIT型肛瘘患者更有可能接受保留括约肌手术（37.0%对3.7%，p<0.001）。
IIT型并不罕见（6.0%），由于肛门外括约肌受累程度更高，应将其视为复杂性肛瘘进行治疗。将IIT型作为Sumikoshi分类系统中的一个新的II型亚类纳入其中，外科医生可能会从中受益。
