Morfologia das fístulas perianais em pacientes com doença de Crohn: avaliação por meio de ressonância magnética

Abstract

Perianal fistulas (PF) are frequently observed in the evolutive course of Crohn's disease (CD), in about 20 to 40% of cases. This study aimed to investigate the morphology of PF in patients with DC who were treated at the Alfa Institute of Gastroenterology, Clinics Hospital of the Federal University of Minas Gerais, which is a referral center for inflammatorybowel disease, using magnetic resonance (MR) imaging of the anal canal, and its correlation with clinical and demographic data. The study consisted of a cross-sectional analytical study (case series), in which, by consecutive sampling (not probabilistic), all patients with CD andPF were included, according to the inclusion criteria, in a period of two years and nine months, coming to a total of 27 cases. The MR scans of the anal canal were performed having as a reference the standardized protocol by Halligan and Stoker, which was established in 2006, with pertinent adaptations, using machines of 1.5 and 3.0 Tesla.Sequences were obtained on oblique transverse and coronal planes oriented orthogonal and parallel, respectively, to the anal sphincter, planned using a midline sagittal image. These sequences were T1 and T2-weighted, with and without fat suppression, before and afterintravenous paramagnetic contrast agent gadolinium. The morphological classification of PF was made according to the criteria established by Parks et al. (1976). Subsequently, the PF were grouped into simple and complex, according to the criteria proposed in 2003 by the American Gastroenterological Association (AGA). Were observed, according to the Parks classification, the relative frequencies of 41.0% (n = 16) for intersphincteric fistulas, 30.8% (n = 12) for transsphincteric, 25.6% (n = 10) for the nonspecific and 2.6% (n = 1) for suprasphincteric. Superficial and extrasphincteric fistulas were not observed. It was found, according to the classification of AGA, the relative frequencies of 74.1% for complex fistulas (n = 20) and 25.9% (n = 7) for the simple fistulas. It was observed that the chance of a patient presenting disease location L2 to develop complex fistula is 164 times higher than for a patient presenting disease location L1 (p-value = 0, 023), whereas the chance of a patient showing disease location L3 is 60 times higher than for a patient presenting disease location L1 (p-value = 0.021). In conclusion, according to the classification of AGA, complex PF predominate over simple PF in patients with CD and PF concurrently; and patients presenting disease location L2 and L3 are more likely to have complex PF than those with L1 disease location