P199 Analysis of clinical features of asymptomatic perianal fistulizing Crohn's disease

Wu, T.(1);Huang, L.(1);Cao, Q.(1);

(1)Sir Run Run Shaw Hospital- College of Medicine- Zhejiang University, Gastroenterology and Hepatology, Hangzhou, China


Perianal fistula represents an aggressive phenotype of Crohn’s disease (CD), and is detected in CD patients without perianal complains. Data of CD patients with asymptomatic perianal fistula is scarce. Our study targets to assess the clinical characteristics of adult CD patients with asymptomatic perianal fistulas in adults with CD.


This retrospectively study collected data from Sir Run Run Shaw Hospital. Newly diagnosed CD patients undergoing magnetic resonance imaging examinations during 2014-2019 were enrolled. The perianal fistulizing CD patients were divided into two groups: 1) symptomatic perianal fistula group, 2) asymptomatic perianal fistula group, then we analyze the features of clinical features, medication and prognosis of each group. 


Among 437 CD patients, 346 (79.2%) had perianal fistulas whereas 91 (20.8%) did not. In patients with perianal fistulas, 89 (25.7%) did not have perianal symptoms. Comparing to symptomatic perianal fistula group, asymptomatic perianal fistula group combined with lower perianal abscess incidence (73.9% vs. 25.8%, p < 0.001). According to Park’s classification, the most common type of fistula in these two groups was intersphincteric fistula (73.2% vs. 53.2% p=0.094). Patients with asymptomatic perianal fistulas were described by the following features when compared with patients with symptomatic perianal fistulas: higher rate of female sex (38.2% vs. 17.9%, p < 0.001), shorter disease duration at enrolment (0.8 vs. 1.0 years, p = 0.001), higher rate of stricturing behavior (32.6% vs. 18.7%, p < 0.01), worse outcomes of laboratory examinations at diagnosis, including hemoglobin (119.0 vs. 131.0 g/dL, p < 0.001) , platelet (333.0 vs. 283.0 *10^9, p < 0.001), ESR (20.0 vs. 14.0 mm/H, p < 0.01) , albumin (35.6 vs. 37.5 g/L, p = 0.001), C-reactive protein (27.3 vs. 15.7 mg/L, p = 0.001). The age at diagnosis and disease locations were not different. For asymptomatic perianal fistula patients, antibiotics (57.3%) and surgery (6.7%) were taken at diagnosis. The usage of biologics at diagnosis showed no difference (59.6% vs. 40.4% p=0.108). Regarding clinical outcomes, the cumulative probabilities for bowel surgery (p < 0.05) and bowel obstruction (p < 0.01) in asymptomatic perianal fistula group were higher than symptomatic perianal fistula group.


Asymptomatic perianal fistulas account for a certain proportion. Female sex, shorter disease duration, stricturing behavior and poor outcomes of laboratory examinations at diagnosis are associated with detection of asymptomatic perianal fistulas. We should pay more attention to CD patients with asymptomatic perianal fistulas because they may have poor prognosis or even worse as patients with symptomatic perianal fistulas.