Colonoscopy accurately predicts the anatomical severity of colonic Crohn's disease attacks: correlation with findings from colectomy specimens

OBJECTIVE: For the assessment of colonic Crohn's disease (CCD) attacks, no clinicobiological and/or morphological (endoscopic, radiological) criteria of severity have been validated in relation to anatomical criteria of severity (ACS) as a gold standard obtained from colectomy specimen examination. Our objective was to assess the accuracy of colonoscopy in predicting the anatomical severity grading of CCD. METHODS: Colectomy specimens from 78 consecutive patients operated between 1982 and 1996 for CCD resistant to medical treatment were analyzed and classified into two groups according to the presence (ACS+) or absence (ACS-) of ACS. These were defined as either deep ulcerations eroding the muscle layer, or mucosal detachments or ulcerations limited to the submucosa but extending to more than one third of one defined colonic segment (right, transverse, left colon). Three endoscopic criteria of severity (ECS) were then defined: 1) deep ulcerations eroding the muscle layer (ECS1), 2) deep ulcerations not eroding the muscle layer but involving more than one third of the mucosal area (ECS2), and 3) mucosal detachment on the edge of ulcerations (ECS3). RESULTS: According to colectomy specimen examination, 68 and 10 patients belonged to ACS+ and ACS- groups, respectively. ECS1, ECS2, and/or ECS3 were found in 70 patients. Positive predictive values of ECS1, ECS2, and ECS3 for the presence of ACS were 90%, 98%, and 92%, respectively. Negative predictive values were 43%, 72%, and 23% respectively. However, at least one ECS (ECS1, ECS2, or ECS3) was found in 95% of patients with ACS. The extent of ulcerations at colonoscopy was correlated to the results of colectomy specimen examination (p < 0.001). Taking into account only patients with ACS, 88% of those with at least one ECS were diagnosed through left side colonoscopy. Usual clinical and biological severity criteria were not different in ACS + and ACS- groups. Two cases of toxic megacolon and toxic shocks were observed after the colonoscopy. CONCLUSIONS: In experienced hands, colonoscopy can be useful in severe CCD attacks. When at least one ECS is found, colonoscopy predicts the anatomical severity of the colitis with a high probability. Conversely, when none of the three ECSs is found, colonoscopy can reasonably exclude the diagnosis of severe anatomical CCD.