Table 2.

Paris classifications of UC and CD[87]

Paris classification of UC
Extent*	E1	Ulcerative proctitis
	E2	Left-sided UC (distal to splenic flexure)
	E3	Extensive (hepatic flexure distally)
	E4	Pancolitis (proximal to hepatic flexure)
Severity	S0	Never severe†
	S1	Ever severe†
Paris classification of CD
Age	A1a	0 to <10
	A1b	10–17
	A2	17– 40
	A3	>40
Location	L1	Distal 1/3 ileal±limited cecal disease
	L2	Colonic
	L3	Ileocolonic
	L4a	Upper disease proximal to the ligament of Treitz
	L4b	Upper disease distal to the ligament of Treitz and proximal to distal 1/3 ileum
Growth	P0	Perianal disease modifier
	G0	No evidence of growth delay
	G1	Growth delay

UC=ulcerative colitis, CD=Crohn’s disease. *Extent defined as maximal macroscopic inflammation.^†Severe defined as a Pediatric Ulcerative Colitis Activity Index score >= 65