Crohn's disease could be missed by ileocolonoscopy if the condition skips the distal ileum or is limited to the mesentary or intramural portion of the bowel wall, but CT enterography can aid detection, according to researchers from the USA. “We wanted to further explore how cross-sectional imaging complements endoscopic assessment,” says David Bruining of the Mayo Clinic, Rochester, Minnesota, USA.

The researchers carried out a retrospective analysis of data from 189 patients with Crohn's disease examined by ileocolonoscopy and CT enterography. The length of terminal ileum examined and presence of inflammation detected by endoscopy and histology were considered. Radiological and biochemical assessments of Crohn's disease and its anatomic locations, as well as the presence of disease-related complications were noted. The reference standard for disease activity was the opinion of the discharging gastroenterologist.

Terminal ileum intubation was carried out on 153 patients during endoscopy and 67 had normal ileoscopy results; 36 of those with normal results were found to have active, small-bowel Crohn's disease. The disease had skipped the terminal ileum in 11 patients and was confined to the intramural or mesenteric distal ileum in 23 patients. Evidence of Crohn's disease was seen by CT enterography in these 34 patients. Two others had disease only in the upper gastrointestinal tract.

These results add to evidence that cross-sectional imaging improves diagnosis rates of IBD. “We plan to prospectively follow patients with terminal ileum skipping in order to better understand the natural history of their disease,” says Bruining.