Comparison of MRI and Endoanal Ultrasound in Assessing Intersphincteric, Transsphincteric, and Suprasphincteric Perianal Fistula.

OBJECTIVES: Perianal fistula is a common disorder characterized by an anomalous perianal track connecting two epithelialized surfaces, most commonly the anal canal and the perianal skin. Although each has its limitations, magnetic resonance imaging (MRI) and endoanal ultrasound are currently two acceptable modalities for assessing perianal fistula. This study aimed to evaluate the accuracy of MRI and endoanal ultrasonography in diagosing perianal fistula, considering the surgical results as the references. METHODS: This prospective cohort study was performed on patients with symptomatic perianal fistulas. MRI results of patients reported by the radiologist were collected along with the findings of endoanal ultrasonography performed by a gastroenterologist. These results were compared with surgical findings as the reference standard. RESULTS: The study enrolled 126 patients. Exactly 222 definitive fistulas were identified during surgery. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of ultrasound for perianal fistula were 87.38, 38.46, 92.38, 26.31, and 82.25% respectively; and for MRI were 76.12, 57.69, 93.88, 22.05, and 74.19% respectively. The accuracy of endoanal ultrasound for detecting transsphincteric and intersphincteric fistulas was higher than MRI. In contrast, the diagnostic value of MRI for detecting suprasphincteric fistulas was higher than endoanal ultrasound. CONCLUSIONS: Using endoanal ultrasonography to diagnose perianal fistulas is a relatively accurate method. This method may be more sensitive than MRI in detecting patients with perianal fistulas and abscesses.

Evaluation of diagnostic accuracy of 3-D endoanal ultrasound in perianal fistula in comparison with intraoperative findings / Avaliação da precisão diagnóstica da USE 3D endoanal em casos de fistula perianal, em comparação com os achados cirúrgicos

ABSTRACT Objective: Perianal fistula is a common and debilitating disease. The definite treatment is surgery, identifying of primary and secondary tract, internal opening of fistula has important role in planning of surgical techniques. This study's goal was to determine the diagnostic accuracy of 3-D ultrasound in perianal fistula in comparison with intraoperative findings. Materials and methods: This study is a cross-sectional study. Adult patients (18-85 years old) with anal fistula have been selected. 3-D EUS was done for all patients by gastroenterologist. Then surgery was done. Check lists filled by endoscopist and surgeon was studied and data analysis was done. Results: The study examined 76 patients, in according to results for kappa coefficient there was a perfect agreement between 3-D ultrasound results and surgery in internal opening that was 96% (p < 0.001) and concordance was 0.974. In extension tract the agreement was 0.973 and concordance was 0.987 (p < 0.001). Conclusion: There was perfect agreement between 3-D ultrasound and surgical findings in internal opening, primary tract and trunk expansion. 3-D ultrasound shows a high diagnostic accuracy when compared with surgery to assessment of perianal fistula before surgery.

RESUMO Objetivo: A fistula perianal é doença comum e debilitante. O tratamento definitivo é cirúrgico. A identificação dos tratos primário e secundário e de abertura interna da fístula desempenha papel importante no planejamento das técnicas cirúrgicas. O objetivo do presente estudo foi determinar a precisão diagnóstica da USE 3D em casos de fístula perianal, em comparação com os achados cirúrgicos. Materiais e métodos: Este é um estudo transversal. Foram selecionados pacientes adultos (18-85 anos) com fístula anal. Todos os pacientes foram examinados por USE 3D realizada por um gastroenterologista. Em seguida, procedeu-se à cirurgia. O endoscopista e o cirurgião estudaram as listas de verificação, com análise dos dados. Resultados: Nesse estudo foram examinados 76 pacientes. De acordo com os resultados para o coeficiente kappa, foi observada perfeita concordância entre os resultados da USE 3D e cirurgia para IO, de 96% (p < 0,001), com concordância de 0,974. Na extensão do trato a concordância foi 0,973 e concordância de 0,987 (p < 0,001). Conclusão: Foi observada concordância perfeita entre USE 3D e os achados cirúrgicos em abertura interna, trato primário e expansão do tronco. USE 3D demonstra elevada precisão diagnóstica, quando comparada com a cirurgia, para avaliação da fístula perianal antes da operação.