| Crohn’s disease | |
| A1 | < 16 years old at diagnosis |
| A2 | 17 to 40 years old at diagnosis |
| A3 | > 40 years old at diagnosis |
| L1 | terminal ileum |
| L2 | colon |
| L3 | ileocolon |
| L4 | upper GI tract |
| L4+ | lower GI tract and distal disease |
| B1 | without stricture formation, nonpenetrating |
| B2 | with stricture formation |
| B3 | internally penetrating |
| B3p | perianally penetrating |
| Ulcerative colitis | |
| E1 | proctitis |
| E2 | left colitis |
| E3 | pancolitis |
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.