Montreal Classification (IBD Phenotype)
Montreal classification of inflammatory bowel disease (Silverberg 2005).
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Crohn age at diagnosis
- A2 — 17–40 years
- Crohn location
- L3 — ileocolonic
- Crohn behavior
- B2 — stricturing
Result: Montreal Crohn’s phenotype A2 L3 B2: A2 (17-40 years), L3 (ileocolonic), B2 (stricturing).
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Crohn’s A / L / B
- Age A1 (<= 16 y), A2 (17-40 y), A3 (> 40 y); location L1 ileal, L2 colonic, L3 ileocolonic, +L4 upper GI; behavior B1 inflammatory, B2 stricturing, B3 penetrating, p perianal.
- UC E / S
- Extent E1 proctitis, E2 left-sided, E3 extensive; severity S0 remission, S1 mild, S2 moderate, S3 severe.
What you enter
- Disease (crohn / uc; defaults to crohn)
- Crohn age at diagnosis (A1-A3)
- Crohn location (L1-L3)
- Isolated upper-GI disease (+L4)
- Crohn behavior (B1-B3)
- Perianal disease (p)
- UC extent (E1-E3)
- UC severity (S0-S3)
How this is calculated
Silverberg MS, Satsangi J, Ahmad T, et al. Toward an integrated clinical, molecular and serological classification of IBD: Report of a Working Party of the 2005 Montreal World Congress of Gastroenterology. Can J Gastroenterol. 2005;19 Suppl A:5A-36A. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.