Montreal Matrix • UC Phenotyping
Extent of Disease (E)
Clinical Severity (S)
Clinical Phenotype
E2S1
E2
Left-sided Colitis
Involvement distal to the splenic flexure.
S1
Mild UC
< 4 stools/day, no systemic toxicity.
Guidelines & Evidence
Verified
Last Review: 2026-07-17
When to Use
When to Use
Defining the extent and severity of Ulcerative Colitis (UC)
Standardizing communication regarding "E" (Extent) and "S" (Severity)
Research-grade phenotypic characterization for longitudinal registries
Philosophy of Montreal (UC)
The UC version of the Montreal classification focuses on the maximal extent of colonic involvement and the clinical severity of the current flare.
How it Works
E: Disease Extent
| E1 (Proctitis) | Limited to the rectum (proximal extent below the rectosigmoid junction). |
| E2 (Left-sided) | Limited to the portion distal to the splenic flexure. |
| E3 (Extensive) | Extends proximal to the splenic flexure (including Pancolitis). |
S: Clinical Severity
| S0 (Remission) | Asymptomatic. |
| S1 (Mild) | ≤ 4 stools/day; no systemic features. |
| S2 (Moderate) | Betwen mild and severe. |
| S3 (Severe) | ≥ 6 stools/day + systemic features (Fever, HR > 90, Hgb < 10.5, or ESR > 30). |
Clinical Pearls
Why Extent Matters
The risk of Colorectal Cancer (CRC) in UC is directly related to the duration and extent of disease. Patients with E1 (proctitis) have a CRC risk similar to the general population, whereas E3 (Extensive) patients require intensive surveillance starting 8 years after diagnosis.
Stability of Extent
UC extent is NOT fixed. Up to 50% of patients with E1 or E2 will progress to a more extensive phenotype over their lifetime. The Montreal stage should reflect the "Maximal Extent Ever Documented."
Clinical Pearls
The S3 (Severe) definition is derived from the original Truelove and Witts criteria
Backwash ileitis (found in some E3 cases) does not change the classification to Crohn's disease
Rectal sparing (macroscopic or microscopic) can occur in UC, especially after treatment, but E1 remains the definition for distal-only disease
Next Steps
Surveillance & Therapy
01
E3 (Extensive): Mandatory CRC surveillance starting 8 years after symptom onset; consider more aggressive maintenance.
02
S3 (Severe): Hospitalize for IV corticosteroids; evaluate using Oxford criteria on Day 3.
Complementary UC Tools
Full Mayo Score for UC
Truelove and Witts Criteria (ASUC)
UCEIS (Endoscopic Index)
The Evidence
The Foundational System
Toward an integrated clinical, molecular and serological classification of inflammatory bowel disease.
Silverberg MS et al. • Can J Gastroenterol.. 2005;19 Suppl A:5A-36A. Landmark global consensus document.
View Source• . ;
Origins & History
Montreal World Congress
Collaboratively refined at the 2005 World Congress of Gastroenterology. It replaced the "Vienna" classification for UC by providing more granular definitions of extent (distinguishing proctitis from left-sided disease).
Last Comprehensive Review: 2026-07-17