Background and study aims: Although hemorrhagic colitis due to enterohemorrhagic Escherichia coli O157:H7 (O157) infection has recently attracted increasing attention as an important enteric infection, the colonoscopic findings associated with this disease have not been sufficiently characterized. The aim of this study is to characterize the colonoscopic features of hemorrhagic colitis due to O157 infection.
Patients and methods: The colonoscopic findings in ten patients with hemorrhagic colitis due to O157 infection were retrospectively reviewed. To assess the severity of inflammation in each part of the large intestine, colonoscopic findings were categorized into four grades: grade 1, intact mucosa; grade 2, sporadic erythema and erosion; grade 3, mostly diffuse inflammation; and grade 4, diffuse, severe inflammation.
Results: Eight out of ten patients had grade 4 findings in the cecum and ascending colon, grade 3 in the transverse colon and descending colon, and grade 2 in the sigmoid colon. Two of these eight patients also had grade 4 inflammation in the proximal transverse colon. Five of these eight patients revealed longitudinal ulcer-like lesions in the transverse colon and/or descending colon. The remaining two patients had grade 3 findings in the cecum to the descending colon and grade 2 findings in the sigmoid colon. All patients exhibited grade 1 finding in the terminal ileum and the rectum. Based on these colonoscopic findings, the ten patients were divided into the typical group (eight patients) and the mild-type group (two patients).
Conclusions: The characteristic colonoscopic findings in most patients with hemorrhagic colitis due to O157 infection were as follows: 1) severe inflammation, including primarily marked edema and facile hemorrhage, and 2) inflammation predominating at the right-side colon; and 3) frequent appearance of longitudinal ulcer-like lesions.