Incidence and Clinical Outcomes of Intersphincteric Abscesses Diagnosed by Anal Ultrasonography in Patients with Crohn's Disease

Background: Intersphincteric abscesses have been reported as uncommon manifestations of perianal Crohn's disease (CD) in surgical series, and may be diagnosed earlier by means of anal ultrasonography. The aim of this study was to evaluate the incidence and outcomes of intersphincteric abscess in a prospective cohort of patients with CD referred for perianal symptoms. Methods: Of the 420 patients with CD attending our outpatient clinic over a period of 5 years, 55 (31 males, mean age 38 6 +/- 13 years) underwent anal ultrasonography because of newly developed symptoms suggesting perianal disease; a clinical evaluation and perianal examination was performed on the same day. Results: An intersphincteric abscess was diagnosed in 23 (42%) of the 55 patients with perianal symptoms, for a total cumulative 5-year incidence of 5% (95% confidence interval [CI]: 3%-7%). During a median follow-up period of 23 months (range 6-53), four of these patients required surgery, four developed a perianal fistula or small ischiorectal abscess not requiring surgery, and 15 experienced a benign course. The patients with a benign course had a longer duration of CD at the time of onset of the perianal symptoms. Conclusions: Intersphincteric abscesses frequently cause perianal symptoms in patients with CD, and their clinical outcomes vary from rapidly progressive inflammation to a benign self-limiting course. The favorable outcome observed in some patients supports a first-line conservative approach to the condition.