Robarts Histopathology Index (Ulcerative Colitis)
The Robarts histopathology index (RHI; Mosli and colleagues, Gut 2017) for histologic activity in ulcerative colitis.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Geboes grade 1, WEIGHT x1
- 2
- Geboes grade 2B, WEIGHT x2
- 1
- Geboes grade 3, WEIGHT x3
- 1
- Geboes grade 5, WEIGHT x5
- 5.0
Result: Robarts Histopathology Index 7 of 33
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Erosion item
- FIVE descriptors, FOUR values: 5.1 and 5.2 both score raw 1. A 0-4 enum would give a max of 38.
- Not inputs
- Geboes grades 0, 2A and 4 (architecture, eosinophils, crypt destruction) contribute 0 at EVERY level.
- Overlap
- Epithelial bands: "<5%" sits inside "<50%", and exactly 50% fits neither. Choose the level, not a percentage.
- Density
- Every integer 0-33 IS attainable, against the intuitive guess that coarse weights leave gaps.
- Remission
- 3 or less on the RHI. NOT the Geboes threshold of 2.0.
- Response
- 9 or less on the RHI. NOT the Geboes threshold of 3.0.
- Scope
- Histologic activity only. Does not diagnose UC, assess dysplasia, or select therapy.
What you enter
- Geboes grade 1, WEIGHT x1
- Geboes grade 2B, WEIGHT x2
- Geboes grade 3, WEIGHT x3.
- Geboes grade 5, WEIGHT x5.
Full field descriptions
- Geboes grade 1, WEIGHT x1 [0 = No increase; 1 = Mild but unequivocal increase; 2 = Moderate increase; 3 = Marked increase]
- Geboes grade 2B, WEIGHT x2 [0 = No increase; 1 = Mild but unequivocal increase; 2 = Moderate increase; 3 = Marked increase]
- Geboes grade 3, WEIGHT x3 [0 = None; 1 = Under 5 percent of crypts involved; 2 = Under 50 percent of crypts involved; 3 = Over 50 percent of crypts involved]. NOTE the bands overlap ("<5%" is inside "<50%") and exactly 50% fits neither - choose the LEVEL, not a percentage.
- Geboes grade 5, WEIGHT x5. Addressed by DESCRIPTOR because 5.1 and 5.2 BOTH score raw 1 [5.0 = No erosion, ulceration or granulation tissue, raw 0; 5.1 = Recovering epithelium with adjacent inflammation, raw 1; 5.2 = Probable erosion, focally stripped, raw 1; 5.3 = Unequivocal erosion, raw 2; 5.4 = Ulcer or granulation tissue, raw 3]
How this is calculated
- Formula
- 1x chronic infiltrate + 2x lamina propria neutrophils + 3x epithelial neutrophils + 5x erosion. 0-33.
Mosli MH, Feagan BG, Zou G, et al. Development and validation of a histological index for UC. Gut. 2017;66(1):50-58. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.