Table 1

Montreal and Paris classification in UC

Montreal22 Paris23
Extent*E1Ulcerative proctitisE1Ulcerative proctitis
E2Left-sided UC (distal to splenic flexure)E2Left-sided UC (distal to splenic flexure)
E3Extensive (proximal to splenic flexure)E3Extensive (hepatic flexure distally)
E4Pancolitis (proximal to hepatic flexure)
SeverityS0Clinical remissionS0Never severe†
S1Mild UCS1Ever severe†
S2Moderate UC
S3Severe UC
  • *Extent defined as maximal macroscopic inflammation.

  • †Severe defined by Paediatric Ulcerative Colitis Activity Index (PUCAI) ≥65.