Table 1.

Pediatric modification of the Montreal classification for inflammatory bowel disease: the Paris classification.

Classification	Montreal	Paris
Age at Diagnosis	A1 <17 year A2 17–40 year A3 above 40 year	A1a 0–10 year A1b 10–17 year A2 17–40 year A3 > 40 year
Location	L1 terminal ileal ± limited cecal disease L2 colonic L3 ileocolonic L4 only upper disease	L1 distal 1/3 ileum ± 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
Behavior	B1 non stricturingnon penetrating B2 stricturing B3 penetrating P perianal disease modifier	B1 non stricturingnon penetrating B2 stricturing B3 penetrating B2B3 both penetrating and stricturing disease, either at the same or different times P perianal disease modifier
Growth	not classified	G0 no evidence G1 growth delay