Abstract Background Perianal fistulizing Crohn’s disease (PFCD) is a common perianal manifestation of Crohn’s disease and is associated with poor prognosis. Some PFCD patients do not exhibit typical anorectal symptoms in early stages, resulting in underdiagnosis, yet they remain at considerable risk for disease progression. Current screening approaches for asymptomatic fistulas differ between Eastern and Western medical practice, partly due to limited knowledge regarding their incidence, natural history, and long-term outcomes in this population. Methods We conducted a retrospective cohort study of 669 PFCD patients from a single center, all with at least 5 years of follow-up, to systematically assess long-term clinical progression and treatment outcomes in asymptomatic fistulas. Patients were stratified according to the presence or absence of perianal symptoms prior to Crohn’s disease diagnosis. Inverse probability weighting was applied to balance baseline confounders. Cox regression and restricted mean survival time analyses were used to compare prognosis and treatment responses between the two groups. Results After a median follow-up of approximately 5 years, perianal symptoms or surgical intervention developed in approximately 31% of patients initially diagnosed with asymptomatic fistulas. Further analysis indicated that asymptomatic patients showed a tendency toward a higher risk of long-term adverse intestinal outcomes, with a hazard ratio of 1.38 for intestinal surgery (P = 0.052). Importantly, initiation of biologic therapy in this group was delayed by an average of 4.92 months (P = 0.030). This treatment delay may contribute to their increased risk of unfavorable outcomes and underscores the importance of early diagnosis and active intervention. Thus, implementing early MRI screening in asymptomatic PFCD patients and promptly adjusting treatment strategies based on imaging findings may help prevent disease progression and improve prognosis. Conclusion This study indicates that patients with asymptomatic PFCD, despite their initially silent clinical presentation, face a substantial risk of disease progression. The trends toward worse outcomes and treatment delays suggest that current diagnostic and management practices may systematically underestimate the disease burden in these patients. We recommend wider adoption of anal MRI screening in newly diagnosed Crohn’s disease patients to facilitate early detection and timely intervention, thereby improving long-term outcomes. References: 1. Kim P H, Park S H, Jin K, et al. Supplementary Anal Imaging by Magnetic Resonance Enterography in Patients with Crohn’s Disease Not Suspected of Having Perianal Fistulas.J. Clinical gastroenterology and hepatology : the official clinical practice journal of the American Gastroenterological Association, 2020,18(2):415-423. 2. Antaya M, Hudson A S, Lerner E P, et al. The impact of integrating pelvic MRI at diagnosis on early detection of perianal Crohn’s disease in pediatricsJ. Am J Gastroenterol, 2025. 3. Anand E, Pelly T, Joshi S, et al. Current practice and innovations in diagnosing perianal fistulizing Crohn’s disease (pfCD): a narrative review.J. Techniques in coloproctology, 2025,29(1):102. Conflict of interest: Dr. Su, Yun: No conflict of interest Zhi, Min: The author declares that she has no competing interests. Zhang, Min: The author declares that she has no competing interests.
Su et al. (Thu,) studied this question.