Review Article

Incidence and Paris Classification of Pediatric Inflammatory Bowel Disease

Table 2

Comparison of Montreal and Paris Classifications for Crohn’s disease based on Levine et al. [13].

Montreal ClassificationParis Classification

Age at diagnosisA1: below 17 years
A2: 17–40 years
A3: above 40 years
A1a: 0–<10years
A1b: 10–<17 years
A2: 17–40 years
A3: >40 years

LocationL1: terminal ileal/
limited cecal disease
L2: colonic
L3: ileocolonic
L4*: isolated upper disease
L1: distal 1/3 ileum
6 limited cecal disease
L2: colonic
L3: ileocolonic
L4a: upper disease proximal to ligament of Treitz* 
L4b: upper disease distal to ligament of Treitz and proximal to distal 1/3 ileum*

BehaviourB1: nonstricturing
nonpenetrating
B2: stricturing
B3: penetrating
p: perianal disease modifier
B1: nonstricturing
nonpenetrating
B2: stricturing
B3: penetrating
B2B3: both penetrating and stricturing disease, either at the same or different times
p: perianal disease modifier

GrowthG0: no evidence of growth delay
G1: growth delay

In both the Montreal and Paris Classification systems L4 and L4a/L4b may coexist with L1, L2, and L3, respectively.