Endoscopic, histological and ultrastructural correlations in the diagnosis of colitis.

The accuracy of the endoscopic diagnosis, found at fiberoptic distal-colonoscopy, was assessed by correlation with the histological findings of multiple colo-rectal biopsies. Of 25 subjects with normal colon at endoscopy, 18 (72%) had normal histology, while 7 (28%) had histological evidence of mild non-specific colitis (6 cases) or Crohn's colitis (one case). Of 15 cases with endoscopic appearance of mild colitis, histological sections showed mild non-specific colitis in 12 (80%), idiopathic ulcerative colitis in one and Crohn's colitis in another. In 12 patients with an endoscopic diagnosis of moderate-severe colitis, histology confirmed moderate to severe idiopathic ulcerative colitis in 9 (75%) and severe Crohn's colitis in 2. Pseudomembranous colitis was confirmed by histology in 2 out of 3 cases detected by endoscopy. Electron-microscopy, although amplifying the histological findings, did not provide any specific diagnostic information. It is concluded that histological studies of multiple colo-rectal biopsies can significantly improve the diagnostic accuracy of distal-colonoscopy. Biopsies should therefore be obtained routinely in colonoscopy even if the appearances look normal.