INTRODUCTION
Anal fistula (AF) is an acquired pathological condition characterized by an abnormal connection between the anal canal and the anoderma or perianal skin, originating from the anal or rectal mucous layer and terminating at the anoderma or perianal skin with opening(s)[1,2]. AF can be caused by the obstruction of anal glands resulting in stasis, infection, and abscess, as well as inflammatory bowel diseases, malignancy, infection, and iatrogenic factors[1-3]. The pathway of AF may traverse the internal anal sphincter (IAS), the external anal sphincter (EAS), both the IAS and EAS, or neither, depending on the AF patterns and complexity[1-5]. AF is not a life-threatening disease, but it significantly impacts the patient's quality of life. Surgery is the classic procedure for the treatment of AF[6-10], and newly emerging intervention treatments are the alternative solutions for AF[5,11-13]. However, some patients experience high recurrence, impairment of anal continence, and even the risk of anal incontinence after surgical removal of the fistula[2,5,8,14]. The ideal treatment approach should aim for no recurrence and no or minimal impact on continence. Successful treatment of AF and associated pathology hinges on accurate evaluation of fistula anatomy, particularly in complex cases. A comprehensive understanding of fistula branches in different anatomic layers would aid in decision-making, effective management, and minimizing the risk of recurrence and injury to the anal sphincters[2-5,13]. For instance, preoperative assessment of the pattern and height of AF is crucial for planning the surgical approach. Low intersphincteric and transsphincteric fistula tracts are typically managed with fistulotomy or fistulectomy. High fistulas that involve more of the IAS or EAS, as well as suprasphincteric and extrasphincteric fistulas, necessitate sphincter-saving procedures to prevent anal incontinence[5-7,10,13]. Fistulotomy and primary sphincteroplasty are commonly used procedures for AF treatment, yielding favorable outcomes in terms of fistula healing with a relatively low risk of incontinence and an acceptable recurrence rate[6,8]. Drainage of an abscess in the EAS space through the IAS space or transanal route can be challenging[6,7]. A trans-sphincteric fistula poses a management challenge, involving the IAS and EAS, often requiring more complex or staged treatment[6,7]. High ligation of the intersphincteric fistula tract through a lateral approach is a sphincter-preserving technique for AF treatment that overcomes the disadvantages of the conventional ligation of the intersphincteric fistula tract technique[6-8].
The diagnosis of AF and associated diseases relies on the patient's medical history, symptoms, signs, physical examinations, and medical imaging studies. While computed tomography (CT) is useful for detecting abscesses and fluid collections, its ability to reveal AF is limited[15,16]. CT-fistulography, interpreted by experienced radiologists, can be a valuable and effective method for identifying fistula pathways[16]. Magnetic resonance imaging (MRI) is considered the most reliable modality for detecting AF due to its ability to provide detailed information on the anal-rectal region and surrounding tissues, assessing complexity, and determining activity levels[17-21]. Endoanal ultrasound (EUS) or 3-dimensional endorectal ultrasound is employed to evaluate the lower rectum, anal sphincters, and pelvic floor, offering visualization of the layers of the rectal wall and anal anatomy[22-24]. The 3-dimensional EUS provides the advantage of visualizing the fistula in different planes and measuring the length of the fistula in the third dimension. Additionally, 3-dimensional EUS can detect the extent of involvement of the IAS and EAS to determine the safe division of the sphincter during fistulotomy[22-24]. However, the efficacy of EUS depends on the expertise of the operator and may not be highly effective in detecting lesions distant from the anal canal[22-24]. When MRI and EUS used together, they can offer comprehensive information on AF, including details on internal and external orifices, pathways in soft tissues, relationships with the IAS and EAS, presence or absence of collections, previous iatrogenic factors, spaces around the IAS and EAS, and the periphery status of AF[22-24]. Some specialists also suggested that to decrease loss of some vital information, a standardized written MRI report of AF can be issued with a short video to highlight the vital parameters of the AF[25].
AF reports in MRI and EUS are composed and issued by radiologists, with the findings described in the reports being referenced by colorectal surgeons. In previous practice, there was a discrepancy in the appropriateness of AF reports between radiologists and colorectal surgeons due to a mutual knowledge gap and lack of necessary information on AF[17-20,26], and some AF reports contain too much information[21,22]. Some AF reports contained abundant information, but colorectal surgeons found it insufficient for decision-making due to the absence of crucial details[18,21,22,26]. Conversely, some AF reports with limited content were deemed deficient in necessary information by colorectal surgeons. To address and reduce this discrepancy, a well-recognized report on the imaging findings of AF should be jointly composed by experts from various specialties, providing valuable and appropriate information for colorectal surgeons. Consequently, various reporting templates have been proposed to describe AF and associated findings[17-20,26]. The goal of establishing a reporting template is to standardize the report, enabling radiologists to deliver essential information for colorectal surgeons and gastroenterologists to aid in decision-making or facilitate communication among radiologists, surgeons, and gastroenterologists. Several versions of reporting templates have been developed by a single academic panel or multiple academic panels comprising radiologists, gastroenterologists, and surgeons[17-19,22,26]. There is considerable heterogeneity in both structured and narrative reporting templates, each with its strengths and limitations, prompting experts to develop new reporting templates or revise existing ones with updated information to enhance the utilization and quality of reporting. Furthermore, with the introduction of new treatment methods, certain items and descriptions of AF and associated structures may need to be added or modified[25]. To meet the requirements of clinical practice, a version of a commonly agreed-upon and highly acknowledged reporting template is essential.
UPDATED SURGEON-ORIENTED REPORTING TEMPLATE
To optimize AF reporting in MRI and EUS, Sudoł-Szopińska et al[27] conceived and designed a study addressing the progress in recent years and proposed a new version of a colorectal surgeon-oriented structured reporting template, which has been published in the World Journal of Gastrointestinal Surgery[27]. There are several strengths of the reporting template[27]: (1) It is based on the Delphi study of a consensus of multidisciplinary and multicenter evidence-based statements, which were generated from 151 selected articles of systematic reviews. In comparison to the source materials used for other reporting templates, the source materials of the present study are richer and more up-to-date, for example, the reporting templates developed by Iqbal et al[18] referred 26 articles, and Halligan et al[19] referred 139 articles. The study involved 69 expert colorectal surgeons, 23 radiologists, 2 anatomists, and 1 gastroenterologist. This composition of panelists, with a higher number of colorectal surgeons from different centers compared to radiologists, reflects a colorectal surgeon-oriented reporting template, and the inclusion of anatomists adds to the unique and rational disciplinary integration. The number of experts in other studies are mainly consisted of radiologists. This reporting template was developed by Delphi process in multidisciplinary group, multicenter, 11 scientific societies, and many countries, with excellent representative and diversity; (2) An interdisciplinary multidisciplinary group anonymously voted in 3 rounds after repeated discussions over 12 months on 14 questions of evidence-based statements. Group consensus was defined as a score of ≥ 8 for ≥ 80% of the panelists, and the degree of agreement was scored on a numeric 0-10 scale. As a result, they achieved consensus for 12 of the 14 statements (85.7%), and the study was endorsed by 3 radiological and 8 surgical scientific societies; and (3) In comparison to narrative reporting, structured reporting template is concise, clear, and radiologist-friendly, it’s convenient for radiologist to efficiently compose a report in short time without missing key information. These results indicate that the reporting template was constructed based on a high level of consensus of evidence and opinions.
