Role of MRI to confirm healing in complex high cryptoglandular anal fistulas: long-term follow-up of 151 cases

The role of MRI in perianal fistulizing disease: diagnostic imaging and classification systems to monitor disease activity

Perianal fistulizing disease, commonly associated with Crohn's disease, poses significant diagnostic and therapeutic challenges due to its complex anatomy and high recurrence rates. Radiological imaging plays a pivotal role in the accurate diagnosis, classification, and management of this condition. This article reviews the current radiological modalities employed in the evaluation of perianal fistulizing disease, including magnetic resonance imaging (MRI), endoanal ultrasound, and computed tomography (CT). MRI, recognized as the gold standard, offers superior soft tissue contrast and multiplanar capabilities, facilitating detailed assessment of fistula tracts and associated abscesses. CT, although less detailed than MRI, remains valuable in acute settings for detecting abscesses and guiding drainage procedures. This article discusses the advantages and limitations of each modality, highlights the importance of standardized imaging protocols, and underscores the need for interdisciplinary collaboration in the management of perianal fistulizing disease. Future directions include advancements in imaging techniques and the integration of artificial intelligence to enhance diagnostic accuracy and treatment outcomes.

Recent advances in the diagnosis and treatment of complex anal fistula

Anal fistula can be a challenging condition to manage, with complex fistulas presenting even greater difficulties. The primary concerns in treating this condition are a risk of damage to the anal sphincters, which can compromise fecal continence, and refractoriness to treatment, as evidenced by a high recurrence rate. Furthermore, the treatment of complex anal fistula involves several additional challenges. Satisfactory solutions to many of these obstacles remain elusive, and no consensus has been established regarding the available treatment options. In summary, complex anal fistula has no established gold-standard treatment, and the quest for effective therapies continues. This review discusses and highlights groundbreaking advances in the management of complex anal fistula over the past decade.

Rectovaginal Fistulas Not Involving the Rectovaginal Septum Should Be Treated Like Anal Fistulas: A New Concept and Proposal for a Reclassification of Rectovaginal Fistulas

Background

Many rectovaginal fistulas(RVF), especially low RVF, do not involve/penetrate the RV-septum, but due to lack of proper nomenclature, such fistulas are also managed like RVF (undertaking repair of RV-septum) and inadvertently lead to the formation of a high RVF (involving RV-septum) in many cases. Therefore, REctovaginal Fistulas, Not Involving the Rectovaginal Septum, should be Treated like Anal fistulas(RENISTA) to prevent any risk of injury to the RV septum. This concept(RENISTA) was tested in this study.

Methods

RVFs not involving RV-septum were managed like anal fistulas, and the RV-septum was not cut/incised. MRI, objective incontinence scoring, and anal manometry were done preoperatively and postoperatively. High RVF (involving RV-septum) were excluded.

Results

Twenty-seven patients with low RVF (not involving RV-septum) were operated like anal fistula[age:35.2±9.2 years, median follow-up-15 months (3-36 months)]. 19/27 were low fistula[<1/3 external anal sphincter(EAS) involved] and fistulotomy was performed, whereas 8/27 were high fistula (>1/3 EAS involved) and underwent a sphincter-sparing procedure. Three patients were excluded. The fistula healed well in 22/24 (91.7%) patients and did not heal in 2/24 (8.3%). The healing was confirmed on MRI, and there was no significant change in mean incontinence scores and anal pressures on tonometry. RV-septum injury did not occur in any patient.

Conclusions

RVF not involving RV-septum were managed like anal fistulas with a high cure rate and no significant change in continence. RV-septum injury or formation of RVF with septum involvement did not occur in any patient. The RENISTA concept was validated in the present study. A new classification was developed to prevent any inadvertent injury to the RV-septum.

Predictors of outcome in cryptoglandular anal fistula according to magnetic resonance imaging: A systematic review

Background and Aims

Anal fistula (AF) with cryptoglandular origin tends to recur, and multiple risk factors are implicated. Recently, some magnetic resonance imaging (MRI) findings with predictive value for disease outcomes have been proposed. These intrinsic anatomic features include those of the AF and its surrounding structures. This study aims to clarify the prognostic role of MRI in AF.

Methods

We performed a systematic search of PubMed, Embase, and EBSCO databases. Two independent reviewers conducted the search and screened the articles. We selected studies that used MRI to assess AF and reported its relationship to disease outcome. We extracted data regarding the study design, type of intervention, outcome, MRI-measured items, and their significance.

Results

Out of 1230 retrieved articles, 18 were eligible for final inclusion, and a total of 4026 patients were enrolled in the selected studies. For preoperative MRI, the significant items affecting the outcome were the length of the fistula, horseshoe type, presence of multiple tracts, supralevator extension, and apparent diffusion coefficient (ADC) value. Other studies investigated the healing process using postoperative MRI.

Conclusion

This review found that MRI can be useful in the management of AF, both preoperatively and postoperatively. Factors, such as fistula length, horseshoe type, presence of multiple tracts, supralevator extension, and ADC value were found to be significantly associated with treatment outcomes. The presence of the fistula tract and the development of new abscesses on postoperative MRI was found to hinder the healing process. Further studies are needed to confirm these findings.

AFCOS: The Development of a Cryptoglandular Anal Fistula Core Outcome Set

OBJECTIVE

To develop a cryptoglandular Anal Fistula Core Outcome Set: a minimum set of outcomes that should be measured in all studies of cryptoglandular anal fistula treatment.

BACKGROUND

Variability in the outcomes that are reported in studies of cryptoglandular anal fistula treatment hampers systematic evidence synthesis to identify the best treatment.

METHODS

This study followed guidance from the Core Outcome Measures in Effectiveness Trials initiative and consisted of three stages: (1) generation of candidate outcomes through systematic review of the literature and qualitative patient interviews; (2) prioritization of outcomes by key stakeholders, including patients, surgeons, gastroenterologists, and radiologists in an online Delphi consensus process; and (3) determination of the final Core Outcome Set (COS) in a consensus meeting attended by patients and clinicians.

RESULTS

Sixty-four outcomes were presented in the first Delphi survey round. A total of 191 participants from over 30 countries ranked these outcomes according to their importance in defining treatment success (57.6% surgeons and gastroenterologists, 8.9% radiologists, and 33.5% patients). After two rounds, 53 outcomes were identified as important and discussed in the consensus meeting attended by 10 patients and 12 clinicians. A final 10 outcomes were voted into the COS: clinical fistula healing, radiological healing, recurrence, development of additional fistulas, fistula symptoms, incontinence, psychological impact of treatment, complications and reinterventions, patient satisfaction, and quality of life.

CONCLUSION

The final COS represents an international, multidisciplinary, patient-centered attempt to establish consistency in fistula research, with a substantial focus on patient priorities for treatment.

A Novel MRI and Clinical-Based Scoring System to Assess Post-Surgery Healing and to Predict Long-Term Healing in Cryptoglandular Anal Fistulas

Background

Anal fistulas cause great uncertainty and anxiety in patients and surgeons alike. This is largely because of the inability to accurately confirm postoperative fistula healing, especially long-term healing. There is no scoring system available that can objectively assess cryptoglandular anal fistulas for postoperative healing and can also accurately predict long-term healing.

Methods

Several parameters that could indicate anal fistula healing were assessed. Out of these, six parameters (four MRI-based and two clinical) were finalized, and a weighted score was given to each parameter. A novel scoring system (NSS) was developed. A minimum possible score (zero) indicated complete healing whereas the maximum weighted score (n = 20) indicated confirmed non-healing. Scoring was done with postoperative MRI (at least 3 months post-surgery), then compared with the actual healing status, and subsequently correlated with the final long-term clinical outcome.

Results

The NSS was validated in 183 operated cryptoglandular fistula-in-ano patients over a 3-year period in whom 283 MRIs (preoperative plus postoperative) were performed. The postoperative follow-up was 12–48 months (median-30 months). The NSS was found to have a very high positive predictive value (98.2%) and moderately high negative predictive value (83.7%) for long-term fistula healing. Additionally, its sensitivity and specificity in predicting healing were 93.9% and 94.7%, respectively.

Conclusion

Thus, this new scoring system is highly accurate and would be a useful tool for surgeons and radiologists managing anal fistulas. By objectivizing the assessment of postoperative healing, it can both ease and streamline management. Moreover, reliable prediction of recurrence-free long-term healing will greatly allay the apprehensions associated with this dreaded disease.

Guidelines on postoperative magnetic resonance imaging in patients operated for cryptoglandular anal fistula: Experience from 2404 scans

Magnetic resonance imaging (MRI) is considered the gold standard for the evaluation of anal fistulas. There is sufficient literature available outlining the interpretation of fistula MRI before performing surgery. However, the interpretation of MRI becomes quite challenging in the postoperative period after the surgery of fistula has been undertaken. Incidentally, there are scarce data and no set guidelines regarding analysis of fistula MRI in the postoperative period. In this article, we discuss the challenges faced while interpreting the postoperative MRI, the timing of the postoperative MRI, the utility of MRI in the postoperative period for the management of anal fistulas, the importance of the active involvement and experience of the treating clinician in interpreting MRI scans, and the latest advancements in the field.