| Score | Longitudinal Extent of Inflammation | Vertical Extent of Inflammation | Histological Changes |
| 0 | none | none | none |
| 1 | patchy | basal lamina propria only | mild loss of differentiated epithelial cells |
| 2 | <50% | transmural | moderate loss of differentiated epithelial cells |
| 3 | >50% | both mucosa and submucosa involved | severe loss of differentiated epithelial cells |