Assessment of perianal fistulizing Crohn’s disease activity with endoanal ultrasound: A retrospective cohort study

Abstract

BACKGROUND Perianal fistulas pose dual challenges to Crohn's disease (CD) patients. Low patient compliance due to the complexity of existing examination methods plagues the treatment and follow-up management of perianal CD. AIM To determine the accuracy of endoanal ultrasound (EUS) and shear wave elastography (SWE) for evaluating perianal fistulizing CD (PFCD) activity. METHODS This was a retrospective cohort study. A total of 67 patients from August 2022 to December 2023 diagnosed with CD were divided into three groups: Non-anal fistula group (n = 23), low-activity perianal fistulas [n = 19, perianal disease activity index (PDAI) ≤ 4], high-activity perianal fistulas (n = 25, PDAI > 4) based on the PDAI. All patients underwent assessments including EUS + SWE, pelvic magnetic resonance [pelvic magnetic resonance imaging (MRI)], C-reactive protein, fecal calprotectin, CD activity index, PDAI. RESULTS The percentage of fistulas indicated by pelvic MRI and EUS was consistent at 82%, and there was good consistency in the classification of perianal fistulas (Kappa = 0.752, P < 0.001). Significant differences were observed in the blood flow Limberg score (χ 2 = 8.903, P < 0.05) and shear wave velocity (t = 2.467, P < 0.05) between group 2 and 3. Shear wave velocity showed a strong negative correlation with magnetic resonance novel index for fistula imaging in CD (Magnifi-CD) score (r = -0.676, P < 0.001), a weak negative correlation with the PDAI score (r = -0.386, P < 0.05), and a weak correlation between the Limberg score and the PDAI score (r = 0.368, P < 0.05). CONCLUSION EUS combined with SWE offers a superior method for detecting and quantitating the activity of perianal fistulas in CD patients. It may be the ideal tool to assess PFCD activity objectively for management strategies.