Appendix 1.
Montreal modification of the Vienna classification of Crohn's disease (adapted from Silverberg MS, et al16)
| Age at diagnosis (A) | |||
|---|---|---|---|
| A1 | 16 years or younger | ||
| A2 | 17-40 years | ||
| A3 | Over 40 years | ||
| Location (L) | Upper GI modifier (L4) | ||
|---|---|---|---|
| L1 | Terminal Ileum | L1 + L4 | Terminal ileum + Upper GI |
| L2 | Colon | L2 + L4 | Colon + Upper GI |
| L3 | Ileocolonic | L3 + L4 | Ileocolonic + Upper GI |
| L4 | Upper GI | ||
| Behavior (B) | Perianal disease modifier (p) | ||
|---|---|---|---|
| B1 | Non-stricturing, non-penetrating | B1p | Non-stricturing, non-penetrating + perianal |
| B2 | Stricturing | B2p | Stricturing + perianal |
| B3 | Penetrating | B3p | Penetrating + perianal |