| Age at diagnosis |
A1:< 17 years |
Severity |
S0: remission, no symptoms |
| A2: 17–40 years |
S1: mild symptoms |
| A3: > 40 years |
S2: moderate symptoms |
|
|
S3: severe symptoms |
| Location, endoscopic or macroscopic estimation |
L1: terminal ileal |
Extensity |
E1: ulcerative proctitis |
| L2: colon |
E2: left-sided UC; distal colitis |
| L3: ileocolon |
E3: extensive UC, pancolitis |
| L4: upper GI modifier: proximal disease with distal disease, such as L1 + L4, L2 + L4, L3 + L4) |
|
| Behavior over time |
B1: non-stricturing, non-penetrating |
|
|
| B2: stricturing |
| B3: penetrating |
| P: perianal disease modifiers, such as B1p, B2p, B3p |
