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.
The Montreal Classification of Crohn’s Disease
| Age at diagnosis | A1: < 17 A2: 17–40 A3: > 40 |
| Location: | L1: ileum L2: colon L3: ileum and colon L4: upper gastrointestinal tract |
| Behavior: | B1: no strictures or fistulas B2: stricturing form B3: fistulasing form p: perianal lesions |
