Female Trans-Sphincteric Anterior Anal Fistula: Still an Unsolved Problem-Results from a Nationwide Cohort Study

Background/Objectives: Female trans-sphincteric anterior anal fistula is one of the most challenging fistulae because of the inherent risk of postoperative incontinence. The objective of this study is to analyze current surgical practices in these patients and their results. Methods: This study is a nationwide cohort retrospective study of all female patients with trans-sphincteric anterior anal fistula that were operated on in 2019. The primary outcomes measured were the analysis of the different techniques used in this type of patient and the results in terms of healing, persistence and recurrence. Results: We analyzed 139 patients that were operated on in 2019 because of an anterior trans-sphincteric fistula. The most usual technique performed was fistulotomy (29.5%), followed by ligation of the inter-sphincteric fistula tract (22.3%). The overall healing rate was 60.4%, taking into account that this rate was higher for fistulotomy (87.8%) than for sphincter-preserving techniques such as ligation of the inter-sphincteric fistula tract, advanced flap and fistulotomy plus sphincterography (51.8%). The main protective factors for healing that have been identified are the absence of current smoking and the realization of a fistulotomy. The overall postoperative incontinence rate is 12.6%, which is higher in patients with higher fistula (25%). It is important to highlight that in low fistula, the rate of incontinence in techniques different from fistulotomy is about 25%. The only risk factor for incontinence that has been identified is obesity. Conclusions: The treatment of this type of fistula is still a big challenge with high diversity in terms of surgical techniques, even though, fistulotomy still remains safe and with good results in terms of healing and incontinence in low fistulas and medium fistulas with strict selection criteria. In these cases, fistulotomy is the indicated procedure.