This calculator is for general information and education. It is not medical advice and does not replace the judgment of a doctor, nurse or pharmacist who knows the full clinical picture.
Measuring ulcerative colitis activity
Ulcerative colitis is an inflammatory disease of the lining of the colon and rectum. It causes bloody diarrhea, urgency and abdominal cramps, alternating with periods of remission. The Mayo score, introduced by Kenneth Schroeder and colleagues at the Mayo Clinic in 1987, is the most widely used measure of its activity in clinical trials and practice.
The four subscores
Each is scored from 0 to 3:
- Stool frequency, compared with the patient’s normal: normal 0, 1 to 2 more 1, 3 to 4 more 2, 5 or more 3
- Rectal bleeding, the worst of the day: none 0, streaks of blood less than half the time 1, obvious blood most of the time 2, blood alone 3
- Endoscopic findings: normal or inactive 0, mild 1, moderate 2, severe with spontaneous bleeding or ulcers 3
- Physician’s global assessment: normal 0, mild 1, moderate 2, severe 3
The partial Mayo score leaves out endoscopy (0 to 9); the full Mayo score includes it (0 to 12).
Example
A patient has 1 to 2 more stools a day than usual (1), streaks of blood less than half the time (1), and the doctor judges the disease mild (1):
- Partial Mayo score: 3, mild activity
If a colonoscopy shows marked erythema, loss of the vascular pattern and erosions (subscore 2), the full Mayo score is 5, still mild.
Interpretation
Partial Mayo score: 0 to 1 remission, 2 to 4 mild, 5 to 6 moderate, 7 to 9 severe.
Full Mayo score: 0 to 2 with no subscore above 1 is remission, 3 to 5 mild, 6 to 10 moderate, 11 to 12 severe.
In practice
The partial score is easy to repeat at each visit or by phone. Treatment targets now go beyond symptoms: the goal is clinical remission (no bleeding, normal stool frequency) and mucosal healing on endoscopy, often with fecal calprotectin as a non-invasive marker. Six or more bloody stools a day with fever, a fast pulse, anemia or a high CRP define acute severe colitis, which requires hospital admission.