title: Endoscopic skipping of the distal terminal ileum in Crohn's disease can lead to negative results from ileocolonoscopy.
abstract: OBJECTIVE
  Crohn's disease often involves the terminal ileum (TI), but skipping of the distal TI can occur. This can lead to negative results from ileocolonoscopy. We analyzed advanced cross-sectional images to determine how frequently this occurs.
  
  
  METHODS
  We analyzed data from 189 consecutive patients (55% women) with Crohn's disease, evaluated in 2009 by computed tomography enterography (CTE) and ileocolonoscopy. The discharge impression of the gastroenterologist who treated the patients was used as the reference standard for Crohn's disease activity.
  
  
  RESULTS
  Of the patients evaluated, 153 underwent TI intubation during endoscopy; 67 of these (43.8%) had normal results from ileoscopy, based on endoscopic appearance. Despite their normal results from ileoscopy, 36 of these patients (53.7%) had active, small-bowel Crohn's disease. The ileum appeared normal at ileoscopy because the disease had skipped the distal ileum of 11 patients (30.6%), developed only in the intramural and mesenteric distal ileum of 23 patients (63.9%), and appeared only in the upper gastrointestinal region of 2 patients (5.6%). These patients had a shorter duration of disease (61.1% for less than 5 years) compared with those found to have Crohn's disease based on ileoscopy (41.1% for less than 5 years; P < .05). CTE detected extracolonic Crohn's disease in 26% of patients; 14% of patients were found to have disorders unrelated to inflammatory bowel disease that warranted further investigation or consultation (including 4 cancers).
  
  
  CONCLUSIONS
  Ileoscopy examination can miss Crohn's disease of the TI because the disease can skip the distal ileum or is confined to the intramural portion of the bowel wall and the mesentery. CTE complements ileocolonoscopy in assessing disease activity in patients with Crohn's disease.
authors.affiliation: Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Sunil
authors.initials: S
authors.lastname: Samuel
authors.forename: David H
authors.initials: DH
authors.lastname: Bruining
authors.forename: Edward V
authors.initials: EV
authors.lastname: Loftus
authors.forename: Brenda
authors.initials: B
authors.lastname: Becker
authors.forename: Joel G
authors.initials: JG
authors.lastname: Fletcher
authors.forename: Jayawant N
authors.initials: JN
authors.lastname: Mandrekar
authors.forename: Alan R
authors.initials: AR
authors.lastname: Zinsmeister
authors.forename: William J
authors.initials: WJ
authors.lastname: Sandborn
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D003424:Crohn Disease / Q000175:diagnosis*; D003951:Diagnostic Errors; D016099:Endoscopy, Gastrointestinal / Q000379:methods*; D005260:Female; D006801:Humans; D007082:Ileum / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D011860:Radiography, Abdominal; D014057:Tomography, X-Ray Computed; D055815:Young Adult