Poster (15W212)

The Prevalence of Abscesses on MRI Assessment of Crohn’s Disease Patients Commencing Anti-TNF therapy for Fistulating Disease


P Brown, F MacCarthy, S McKiernan, N Mahmud, D Kevans


Department of Gastroenterology, St James’s Hospital, Dublin 8. School of Medicine, Trinity College Dublin, Dublin


The presence of perianal Crohn’s disease (CD) is an established indication for the initiation of anti-TNF therapy. The exclusion of active perianal sepsis prior to the initiation of anti-TNF therapy is an important clinical issue. Perianal MRI has become an essential imaging modality in this regard allowing the definition of the extent of fistulating disease and the exclusion of perianal sepsis (1). We aimed to define the prevalence of perianal sepsis in CD patients commencing anti-TNF therapy for fistulating disease and determine whether serum CRP was associated with the presence of perianal sepsis.


We retrospectively examined the records of Crohn’s disease patients attending a single academic medical centre with an available baseline pelvic MRI performed prior to the initiation of anti-TNF therapy for perianal disease. All imaging was reviewed by an experience GI radiologist and the presence or absence of fistulae and abscesses determined. For each included subject serum CRP performed within one month of baseline MRI was collected. Serum CRP values were compared between subjects with and without perianal abscess using Student’s T-test.


31 patients (20 female, 11 male) with perianal Crohn’s disease treated with anti-TNF therapy with available perianal MRI data were identified. Age (mean ± standard deviation) was 36 ± 13 years. 10 subjects (32%) had a perianal abscess at baseline MRI assessment. There was a numerical trend towards higher CRP values in subjects with a perianal abscess, mean CRP 54.4mg/L vs 25.47mg/L, p=0.28, however this difference did not reach statistical significance.


Approximately a third of patients commencing anti- TNF therapy for perianal Crohn’s disease, have a perianal abscess at baseline on MRI evaluation. A significantly elevated serum CRP should raise the clinical suspicion of a perianal sepsis. These data highlight the importance of perianal imaging or an examination under anaesthesia to exclude perianal sepsis prior to the initiation of anti-TNF therapy.