Criteria for microscopic assessment of colonic damage
| Severity of crypt destruction | Grade of injury |
| aCrypt lesion | |
| Intact crypt | 0 |
| Loss of basal third | 1 |
| Loss of two thirds | 2 |
| Loss of entire crypt | 3 |
| Erosion | 4 |
| bDamaged area | |
| 1–25% | 1 |
| 25–50% | 2 |
| 50–75% | 3 |
| 75–100% | 4 |
| cInflammation | |
| Absent | 0 |
| Light | 1 |
| Moderate | 2 |
| Severe | 3 |
| dCrypt distortion | |
| Absent | 0 |
| Light | 1 |
| Moderate | 2 |
| Severe | 3 |
Final score: (a × b) + c + d.