‘PAID’ scheme for summarising IBD biopsy histology
| Pattern | Recorded as text; no code | |
| Activity | ||
| Grade (at each site) | Criteria* | Code |
| None | No intraepithelial neutrophils, erosions, or ulcers | A0 |
| Mild | Cryptitis in up to 25% of crypts/crypt abscesses in up to 10% of crypts/both | A1 |
| Moderate | Cryptitis in >25% of crypts/crypt abscesses in >10% of crypts/sparse small foci of surface erosion/combinations | A2 |
| Severe | Ulceration or multiple foci of erosion | A3 |
| Interpretation | ||
| IBD—probability† | Comment | Code |
| IBD definite/very likely | Histology is of IBD, or is highly suggestive/supportive of IBD. Subcategorise as below | IBD-DVL |
| IBD favoured over other causes | Histology is more likely to be IBD than other causes, but is not convincing. Subcategorisation may be inappropriate | IBD-F |
| No evidence of IBD | IBD-0 | |
| Subcategory of IBD† | ||
| UC definite/very likely | Histology is of UC, or strongly favours UC over CD | UC-DVL |
| UC favoured over CD | Histology does not distinguish, but favours UC over CD | UC-F |
| IBD unclassified | Neither UC nor CD is favoured | IBDU |
| CD favoured over UC | Histology does not distinguish, but favours CD over UC | CD-F |
| CD definite/very likely | Histology is of CD, or strongly favours CD over UC | CD-DVL |
| Dysplasia | ||
| Grade | Comment | Code |
| No dysplasia | D0 | |
| Low-grade dysplasia | Specify site(s), and number of biopsies involved | DL |
| High-grade dysplasia | Specify site(s), and number of biopsies involved | DH |
| Indefinite for dysplasia | Unclassifiable atypia | DI |
*Modified from previous schemes.3 ,12 ,40 ,52 ,53
†In conjunction with the clinical picture.
CD, Crohn's disease; DH, dysplasia, high grade; DL, dysplasia, low grade; DVL, definite or very likely; F, favoured; IBD, inflammatory bowel disease; IBDU, inflammatory bowel disease, unclassified; UC, ulcerative colitis.