Clinical and magnetic resonance imaging spectrum of complex perianal fistulizing Crohn's disease: A cohort study from northern India.

BACKGROUND: Fistulizing perianal Crohn's disease (CD) is a debilitating condition associated with significant morbidity and reduction in the quality of life. Magnetic resonance imaging (MRI) of the pelvis is the preferred imaging modality for the comprehensive assessment of the perianal fistula. There is a paucity of data from India on the MRI spectrum of complex perianal fistula in CD. METHODS: A single-centre cross-sectional analysis of patients with fistulizing perianal CD, who underwent pelvic MRI between January 2020 and December 2021, was performed. The clinical (age, sex, disease duration, disease location and behavior, disease activity [Perianal Disease Activity Index, PDAI] and treatment received) and radiological (number and location of fistulae, extensions, number and location of internal and external openings, fistula activity, presence or absence of perianal abscess and associated proctitis) characteristics of complex perianal fistula (defined according to the American Gastroenterological Association classification) were recorded. RESULTS: Of total 175 patients with CD who attended the gastroenterology clinic during the study period, 27 (15.42%) (mean age 42±15.5 years, 62.96% females and median disease duration four years) had complex perianal fistula and were included in the analysis. The mean PDAI was 5.48±2.53. The median Van Assche Index was 17 (interquartile range [IQR] 13-19). A majority (96.29%) of the fistulae were trans-sphincteric and four (14.81%) fistulae extended into the supralevator space. All fistulae were active on MRI. Concomitant perianal abscess and proctitis were seen in 59.26% (n=16) and 62.96% (n=17) of patients, respectively. Combination therapy with biologics and antibiotics/immune-suppressants were the most commonly prescribed medical therapy. Six (22.22%) patients underwent combined medical and surgical (non-cutting seton, fistulectomy, fecal diversion) treatment. CONCLUSION: The cumulative risk of the development of fistulizing perianal CD in a northern Indian cohort was similar to the western populations. Complex perianal fistulae were predominantly trans-sphincteric and commoner in females. MRI evaluation is pivotal for the delineation of fistula anatomy, assessment of disease extent and activity and the evaluation of concomitant perianal abscess and other complications.