Clinical Features and Short-Term Disease Progression of Asymptomatic Perianal Fistulizing Crohn's Disease

Anal imaging improves the diagnosis of perianal diseases in Crohn's disease (CD) patients, especially those with no perianal symptoms. However, the clinical characteristics and outcomes of CD patients with asymptomatic perianal fistula are unknown. This study aims to explore the prevalence and clinical course of Chinese CD patients with asymptomatic perianal fistula in a hospital-based cohort.

We performed a retrospective cohort study of consecutive hospitalized patients with newly diagnosed CD in China. Asymptomatic perianal fistula patients with CD were defined as those who exhibited fistula tracts on magnetic resonance imaging scans, absence of reported perianal symptoms, or any prior history of perianal fistula. Their clinical features and prognosis were reviewed and analyzed.

Among 376 patients who underwent anal imaging, 93 (24.73%) had asymptomatic perianal fistula, 187 (49.73%) had symptomatic perianal fistula, and 67 patients (17.82%) showed no perianal involvement. There were significant differences among patients without perianal lesions, patients with symptomatic perianal fistula, and patients with asymptomatic perianal fistula in the proportion of male sex (49.25% vs. 84.49% vs. 64.52%, respectively; p < 0.001), age at diagnosis (median 32.00 vs. 26.00 vs. 24.00, p < 0.01), disease location (p < 0.05), and laboratory examination. Patients with asymptomatic perianal fistula had a higher cumulative incidence of abdominal surgery (p < 0.001) and intestinal obstruction (p < 0.05).

Patients with asymptomatic perianal fistulas account for a certain proportion of CD patients at diagnosis, with a higher proportion of stricturing behavior and cumulative incidence of intestinal obstruction and CD-related bowel surgery.