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Scientific Session 02 — Gastrointestinal - Bowel

Monday, May 1, 2017

Abstracts 1014-2989

2950. MRI Features of Perianal Fistulas: Is There a Difference Between Crohn’s and non-Crohn’s Patients?

Oliveira I*,  Kilcoyne A,  Harisinghani M. Massachusetts General Hospital, Boston, United States

Address correspondence to I. Oliveira (

Objective: Though perianal fistulas are commonly seen in patients with Crohn disease, they can also be seen in patients without inflammatory bowel disease. The purpose of this study was to evaluate MRI differences of perianal fistulas in patients with and without Crohn disease.

Materials and Methods: Our retrospective search from January 2012 to December 2015 of the radiology database for perianal fistula yielded 207 patients. Only patients with dedicated fistula protocol studies were included; patients with previous anal surgery or anastomosis, anorectal tumors, and equivocal findings that could not be definitely assessed as a fistula were excluded. The following features were assessed: anatomic type of fistula (Parks classification), luminal origin (clock referent), anal verge distance, signs of acute inflammation, circumference of anus involved by inflammation, and presence of rectal inflammation and abscess.

Results: Out of the 207 patients, 126 met inclusion criteria. Of these, 96 (76.2%) patients had Crohn disease; 30 (23.8%) did not. The most common fistulas identified were transsphincteric (38.5% of patients with Crohn disease and 50% of those without) and intersphincteric (33.3% of patients with Crohn disease and 35.4% of those without). An abscess was associated in 41 cases: 32 (33.3%) patients with Crohn disease and nine (30.0%) without. Rectal inflammation was present in 29 (29.2%) patients with Crohn disease and in two (6.7%) without Crohn’s. This finding was statistically significant (p = 0.0009).

Conclusion: Our study demonstrates that although both groups can have similar MRI features, accompanying rectal inflammation was more commonly seen in patients with Crohn disease than in those without.