Montreal Classification of UC: Extent and Severity

Assign Montreal extent (E1–E3) and severity (S0–S3), the phenotype used for prognosis, surveillance planning and research coding.

Adults with established ulcerative colitis, in clinic. This is PHENOTYPING, not the acute assessment: extent is the maximum ever documented and changes over years. For 'is this acute severe colitis right now', use the Acute Severe UC (modified Truelove-Witts) tool, it asks different questions at different thresholds. Not for paediatric patients. Use the Paris classification. Do not enter protected health information.

Caveats

Extent means the maximum ever documented

Extent can both progress and regress, and a quiescent colon can look far more limited than it is. Classify on the maximum extent ever documented, not on the most recent scope.

“Disease extent can change after diagnosis. 29 Up to half with proctitis or proctosigmoiditis will develop more extensive disease. 8 26 30 Of patients with proctitis initially, 10% will ultimately have extensive colitis. 31 However, over time the extent of inflammation can also regress, and classification should always remain as the maximal extent.”

British Society of Gastroenterology consensus guidelines on the management of inflammatory bowel disease in adults. · 2019 · PMID 31562236

S3 is NOT the same test as Truelove-Witts

Montreal S3 and the modified Truelove-Witts criteria overlap but are different tests at different thresholds: S3 uses temperature >37.5 C and ESR >30 mm/h, Truelove-Witts uses >37.8 C and CRP >30 mg/L. A patient can be S3 without meeting Truelove-Witts, and the reverse. S3 is a PHENOTYPE label; the decision to admit for acute severe colitis is a separate assessment -- use the Acute Severe UC tool for that, and do not read S3 off this page as an admission trigger.

“The criteria proposed by Truelove and Witts (TW) more than 70 years ago remain the most commonly used for initial risk stratification of patients with ASUC [7]. These criteria were based on clinical symptoms (including the presence of ≥ 6 bloody stools/day) and laboratory features of systemic inflammation (at least one of the following signs of systemic inflammation: heart rate > 90 beats/min, temperature > 37.8 ◦ C, hemoglobin < 105 g/L and/or erythrocyte sedimentation rate (ESR) >30 mm/h). These criteria were later modified to include elevated C-reactive protein (CRP) >30 mg/L instead of raised ESR”

Predicting Outcome after Acute Severe Ulcerative Colitis: A Contemporary Review and Areas for Future Research. · 2024 · PMID 39124775