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GastroAGI flagship

1
MASLD–MASH NITIntegrated non-invasive assessment of MASLD fibrosis and at-risk MASH — FIB-4, APRI, NFS, FAST, Agile 3+, Agile 4, ELF and ADAPT in one pass

Most used

21
MELD-NaAssesses the severity of chronic liver diseaseChild-Pugh ScoreAssesses the prognosis of chronic liver disease, mainly cirrhosisFIB-4 IndexLiver fibrosis scoring indexAPRIAST to platelet ratio — liver fibrosisMaddrey's DFAlcoholic hepatitis severityGlasgow-BlatchfordUpper GI bleed risk stratificationGAHSGlasgow alcoholic hepatitis scoreMontreal IBDIBD classification — CD & UCMayo ScoreUlcerative colitis activityBISAP ScoreBedside index for severity of pancreatitisCLIF-SOFAOrgan failure scoring in cirrhosisAlcohol ContentStandard drinks & alcohol grams calculatorAARC-ACLFAcute-on-chronic liver failure gradePELD / CR ScorePediatric end-stage liver diseaseHarvey-BradshawCrohn's disease activity indexCTSICT severity index — pancreatitisRockall ScoreGI bleed rebleeding & mortality riskCAGEAlcohol use disorder screening (4 questions)MELD 3.0Updated MELD — sex-inclusive formulaAUDIT ScoreAlcohol use disorders identification testVOCAL-Penn ScorePost-operative mortality risk in cirrhosis surgery

Liver & Cirrhosis

17
ALBI GradeAlbumin-bilirubin liver function grade in HCCUKELD ScoreUK model for end-stage liver diseaseMELD-XIMELD excluding INR — for anticoagulated patientsWest Haven CriteriaHepatic encephalopathy gradingMilan CriteriaLiver transplant eligibility in hepatocellular carcinomaLI-RADS v2018 (CT/MRI)Liver observation category from size, APHE and major featuresBCLC StagingHepatocellular carcinoma stage and treatment allocationSimplified AIH CriteriaSimplified criteria for autoimmune hepatitisRevised Original AIH ScoreIAIHG 1999 comprehensive autoimmune hepatitis scoreSAAGSerum-ascites albumin gradient — cause of ascitesR FactorHepatocellular vs cholestatic pattern in liver injuryCLIF-C ACLFMortality prediction in acute-on-chronic liver failureKing's College CriteriaTransplant criteria in acute liver failureGALAD ScoreHCC detection from gender, age, AFP-L3, AFP and DCPMetroticket 2.0AFP-adjusted up-to-seven for HCC transplant eligibilityRUCAMCausality in drug- and herb-induced liver injuryBaveno VII CriteriacACLD, CSPH and sparing screening endoscopy

Fibrosis & MASLD

8
NAFLD Fibrosis ScoreAdvanced fibrosis probability in MASLD/NAFLDBARD ScoreBMI, AST/ALT ratio, diabetes — MASLD fibrosisFatty Liver IndexPredicts hepatic steatosis from routine labsFibrotic NASH Index (FNI)At-risk NASH probability from AST, HbA1c and HDLNAFLD Activity Score (NAS)Histologic activity grade — steatosis, inflammation, ballooningMEFIB IndexMRE + FIB-4 rule for significant fibrosis (≥F2) in MASLDFAST ScoreFibroScan-AST — at-risk NASH from LSM, CAP and ASTSAFE ScoreSteatosis-Associated Fibrosis Estimator for MASLD in primary care

Pancreas & Biliary

8
Ranson's CriteriaAcute pancreatitis severity at 48 hoursGlasgow-Imrie CriteriaAcute pancreatitis severity — the PANCREAS criteriaHAPSHarmless acute pancreatitis scoreTokyo Guidelines — CholangitisTG18 diagnosis and severity grade for acute cholangitisTokyo Guidelines — CholecystitisTG18 diagnosis and severity grade for acute cholecystitisBiliary Pain (Rome IV)Rome IV — defining biliary-type pain before interventionFunctional Pancreatic SODRome IV — pancreatic sphincter of Oddi disorderRevised Atlanta ClassificationAcute pancreatitis severity — mild, moderately severe, severe

IBD

9
Truelove & Witts CriteriaAcute severe ulcerative colitis — admission decisionUCEISUlcerative colitis endoscopic index of severitySCCAISimple clinical colitis activity index — symptoms onlyCDAICrohn's disease activity index — the trial standardSES-CDEndoscopic severity in Crohn's diseasePUCAIPaediatric ulcerative colitis activity indexTravis (Oxford) CriteriaDay 3 colectomy risk in acute severe ulcerative colitisHo IndexDay 3 steroid failure risk in acute severe ulcerative colitisRutgeerts ScorePostoperative Crohn's recurrence at ileocolonoscopy

GI Bleeding

7
EVendo ScorePredicts oesophageal varices needing treatmentForrest ClassificationPeptic ulcer bleeding — rebleeding risk at endoscopyAIMS65 ScoreUpper GI bleed mortality — five bedside criteriaOakland ScoreSafe-discharge risk for acute lower GI bleedingABC ScoreAge, blood tests, comorbidities — GI bleed mortalitySarin ClassificationEndoscopic classification of gastric varicesEGUS (Gastric Ulcer)Malignancy risk in a gastric ulcer, and who needs repeat endoscopy

Alcohol

2
ABIC ScoreAge, bilirubin, INR, creatinine — alcoholic hepatitisLille ModelSteroid response at day 7 in alcoholic hepatitis

Upper GI

4
Chicago Classification v4.0Oesophageal motility pattern from high-resolution manometryLA Classification (Oesophagitis)Los Angeles grade A–D for erosive oesophagitisPrague C & M CriteriaCircumferential and maximal extent of Barrett's oesophagusEREFS (Eosinophilic Oesophagitis)Endoscopic reference score — oedema, rings, exudates, furrows, stricture

Colorectal

3
Boston Bowel Prep ScaleColonoscopy preparation adequacy by segmentStool Osmotic GapOsmotic vs secretory diarrhoea from stool electrolytesATLAS Score (C. difficile)Predicted response to therapy in Clostridioides difficile infection

Functional GI

37
Bristol Stool ScaleStool form types 1–7 and colonic transitRome IV Criteria for IBSIrritable bowel syndrome diagnosis and subtypeFunctional ConstipationRome IV — two of six items, IBS excludedOpioid-Induced ConstipationRome IV — constipation tied to opioid therapyFunctional DiarrhoeaRome IV — loose stools without predominant painFunctional Bloating / DistensionRome IV — bloating without other bowel disorder criteriaUnspecified Functional Bowel DisorderRome IV — bowel symptoms fitting no other categoryCentrally Mediated Abdominal Pain (CAPS)Rome IV — continuous pain unrelated to gut eventsNarcotic Bowel SyndromeRome IV — opioid-induced hyperalgesia of the gutFaecal Incontinence (Rome IV)Rome IV — the criteria, and why nobody is askedFunctional Anorectal PainLevator ani, unspecified pain and proctalgia fugaxFunctional Defecation DisordersRome IV — dyssynergia and inadequate propulsionInfant RegurgitationRome IV — the happy spitter, and the alarm features that rule it outInfant ColicRome IV — recurrent unexplained crying in a well infant under 5 monthsInfant DyscheziaRome IV — straining before a soft stool, and why not to intervenePaediatric Functional ConstipationRome IV — two of six over one month, with overflow soiling as a criterionToddler's DiarrhoeaRome IV functional diarrhoea of childhood — painless, thriving childPaediatric Cyclic Vomiting SyndromeRome IV — both age bands, with different criteria for eachPaediatric Rumination SyndromeRome IV — infant and child/adolescent criteriaFunctional Nausea & Vomiting (Children)Rome IV — two separate disorders that can be met togetherAerophagiaRome IV — distension that increases through the dayPaediatric Functional DyspepsiaRome IV — four times a month, with PDS and EPS subtypingPaediatric Irritable Bowel SyndromeRome IV — plus the constipation clause clinicians missAbdominal MigraineRome IV — stereotypical incapacitating episodes weeks apartFunctional Abdominal Pain — NOSRome IV — the residual category, reached after the other threeNonretentive Faecal IncontinenceRome IV — soiling without retention, where laxatives make it worseFunctional DyspepsiaRome IV — with PDS and EPS subtypingRumination SyndromeRome IV — effortless regurgitation without retchingCyclic Vomiting SyndromeRome IV — stereotypical episodic vomitingCannabinoid HyperemesisRome IV — CVS pattern relieved by cannabis cessationChronic Nausea & VomitingRome IV — chronic nausea and vomiting syndromeBelching DisordersRome IV — supragastric vs gastric belchingFunctional HeartburnRome IV — heartburn with normal acid exposureReflux HypersensitivityRome IV — normal acid exposure, positive symptom associationFunctional Chest PainRome IV — non-cardiac, non-reflux chest painGlobusRome IV — painless lump-in-throat sensationFunctional DysphagiaRome IV — dysphagia with normal endoscopy and manometry
  1. Calculators
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  3. Mayo Score
IBDMost used

Mayo Score

Ulcerative colitis activity

Relative to that patient's own baseline, not an absolute count.

This is the Mayo endoscopic subscore. Mucosal healing is usually defined as 0 or 1.

The full score runs 0–12. Dropping the endoscopic subscore gives the partial Mayo score, which can be calculated without a scope.

When to use
Use it to quantify ulcerative colitis activity at diagnosis, to judge response to treatment, and to define remission — it is the instrument almost every UC trial has used as its primary endpoint, which is why treatment thresholds in guidelines are expressed in its terms. In clinic, the partial Mayo score is the practical version for follow-up between endoscopies, and the endoscopic subscore is what determines whether mucosal healing has been achieved. It is not a severity score for acute severe colitis — Truelove and Witts criteria are used for that admission decision — and it does not assess disease extent, which is what the Montreal classification records.
Why use it
Because it is the common language of ulcerative colitis outcomes. When a guideline says a therapy achieves remission in a given proportion of patients, or a trial reports mucosal healing rates, those numbers are almost always Mayo-defined, so scoring a patient the same way is the only means of relating their situation to the evidence. It also separates symptoms from inflammation deliberately: a patient can feel considerably better while the endoscopic subscore stays at 2, and the score makes that divergence visible rather than letting symptomatic improvement stand in for healing.
Formula, evidence and interpretation

About the Mayo Score for Ulcerative Colitis (Disease Activity Index)

The Mayo score grades ulcerative colitis activity from four items, each scored 0 to 3: stool frequency, rectal bleeding, the endoscopic appearance of the mucosa, and the physician's global assessment. The total runs from 0 to 12, with 0–2 taken as clinical remission, 3–5 mild, 6–10 moderate and 11–12 severe activity. Dropping the endoscopic item gives the partial Mayo score (0–9), which can be calculated without a scope, and the endoscopic item on its own is the Mayo endoscopic subscore that defines mucosal healing at 0 or 1.

On this page

  • Formula
  • Interpreting the result
  • Inputs
  • What it returns
  • How it is calculated
  • Facts & figures
  • Evidence
  • How it compares
  • Pearls & pitfalls
  • Critical actions
  • Why it exists
  • About the creator
  • Limitations
  • If you are the patient
  • FAQ
  • Related calculators
  • References

Formula

Full Mayo score = stool frequency + rectal bleeding + endoscopic appearance + physician global assessment Partial Mayo score = stool frequency + rectal bleeding + physician global assessment Each item scores 0–3. Full range 0–12, partial range 0–9.
Stool frequency
0 = normal for this patient; 1 = 1–2/day above normal; 2 = 3–4/day above; 3 = more than 4/day above.
Rectal bleeding
0 = none; 1 = streaks less than half the time; 2 = obvious blood most of the time; 3 = blood alone.
Endoscopic appearance
0 = normal/inactive; 1 = mild; 2 = moderate; 3 = severe. This item alone is the Mayo endoscopic subscore.
Physician global assessment
0 = normal; 1 = mild; 2 = moderate; 3 = severe.
  • There is no weighting — all four items contribute equally, which is a known limitation given that endoscopic activity predicts outcome better than the symptom items.
  • Stool frequency is relative to the patient's own baseline. This is the item most often scored incorrectly.
  • Definitions of remission vary between trials. Many require both a total of 2 or below and no individual subscore above 1, which is stricter than the total alone.

Interpreting the result

Read three numbers, not one. The total places the patient in a remission-to-severe band and is what trial comparisons use. The endoscopic subscore is the number that predicts what happens next: healing at 0 or 1 predicts sustained remission, and a patient whose symptoms have resolved while the subscore remains 2 or 3 is not in remission in any meaningful sense. The partial score is what you can track at every visit without a scope. Where symptoms and endoscopy diverge, believe the endoscopy — and remember that ongoing symptoms with a healed mucosa often mean something other than active inflammation, such as coexisting irritable bowel syndrome or bile-acid diarrhoea.

ScoreBandWhat it meansAction
0–2Clinical remissionRemission. Most trial definitions additionally require no individual subscore above 1Continue maintenance therapy; confirm mucosal healing endoscopically rather than relying on symptoms
3–5Mild activityMildly active diseaseOptimise topical and oral 5-ASA; check adherence before escalating
6–10Moderate activityModerately active diseaseEscalate — steroids for induction with a non-steroid maintenance plan; consider biologic or small-molecule therapy; exclude C. difficile and CMV
11–12Severe activitySeverely active diseaseAssess for acute severe ulcerative colitis with Truelove and Witts criteria; may need admission, IV steroids and early surgical involvement

Scroll the table sideways for every column.

What the Mayo Score needs (4 inputs)

Stool frequency (0–3)
Scored against that patient's own pre-illness baseline, not an absolute count: 0 for normal, 1 for 1–2 more per day, 2 for 3–4 more, 3 for more than 4 above normal. Using an absolute number is the commonest scoring error.
Rectal bleeding (0–3)
0 for none, 1 for streaks of blood less than half the time, 2 for obvious blood most of the time, 3 for blood passed alone. Reflects the most severe bleeding of the day.
Endoscopic appearance (0–3)
The Mayo endoscopic subscore: 0 normal or inactive, 1 mild (erythema, decreased vascular pattern, mild friability), 2 moderate (marked erythema, absent vascular pattern, friability, erosions), 3 severe (spontaneous bleeding, ulceration). Scored on the worst-affected segment seen.
Physician global assessment (0–3)
0 normal, 1 mild, 2 moderate, 3 severe — an overall clinical judgement taking the other findings, examination and the patient's functional state into account. It is the most subjective item and the one that varies most between assessors.

Units. There are no laboratory values and no unit conversions in this score — every item is a clinical or endoscopic grade. The one thing that must be standardised is stool frequency, which is scored relative to the patient's own pre-illness baseline rather than as an absolute number per day. Establish and record that baseline, because without it the item cannot be scored consistently between visits or between clinicians.

What it returns

Full Mayo score (0–12)
The sum of all four items. Requires endoscopy, so in practice it is calculated at diagnosis and at defined reassessment points rather than at every visit.
Partial Mayo score (0–9)
The three non-endoscopic items. Validated as a proxy for the full score and the practical instrument for clinic follow-up; remission is usually taken as 2 or below with no subscore above 1.
Mayo endoscopic subscore (0–3)
The endoscopic item alone. Mucosal healing is conventionally defined as 0 or 1, and it predicts sustained remission better than symptoms do.

How it is calculated

The index was described in a 1987 placebo-controlled trial of coated oral 5-aminosalicylic acid in 87 patients with mildly to moderately active ulcerative colitis, which is why it is sometimes called the Schroeder index. Its structure is intentionally plain: four domains covering symptoms, endoscopy and clinician judgement, each on the same four-point scale, summed without weighting. That simplicity is why it was adopted so widely as a trial endpoint, and also why several of its known weaknesses persist — an equally weighted physician global assessment carries as much numerical influence as the endoscopic appearance, despite the latter being far more predictive of long-term outcome.

Facts & figures

The four items
Item0123
Stool frequencyNormal for patient1–2/day above normal3–4/day above normal> 4/day above normal
Rectal bleedingNoneStreaks < half the timeObvious blood most of the timeBlood alone passed
Endoscopic appearanceNormal / inactiveErythema, decreased vascular patternMarked erythema, friability, erosionsSpontaneous bleeding, ulceration
Physician global assessmentNormalMildModerateSevere

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Which version to use when
VersionRangeNeeds endoscopyTypical use
Full Mayo score0–12YesTrial endpoints, diagnosis, formal reassessment
Partial Mayo score0–9NoRoutine clinic follow-up between endoscopies
Mayo endoscopic subscore0–3YesDefining mucosal healing (0 or 1); predicting sustained remission

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Evidence

Description — Schroeder trial of coated oral 5-ASA

1987 · n = 87

A double-blind, placebo-controlled trial in 87 patients with mildly to moderately active ulcerative colitis over six weeks, in which outcomes were assessed by flexible proctosigmoidoscopy and physician assessment at three-week intervals alongside patient-recorded daily symptoms. The index used to combine those assessments became the Mayo score.

Partial Mayo score validation

2008

The three-item score omitting endoscopy has been validated against the full score and is widely used for follow-up where repeat endoscopy is impractical.

Correlates closely with the full Mayo score and responds to treatment similarly, which is what supports its use between endoscopic assessments.

Endoscopic subscore and long-term outcome

2024

Studies of mucosal healing in ulcerative colitis have repeatedly shown that the endoscopic subscore predicts colectomy-free survival and sustained remission better than symptom-based measures.

A subscore of 0 or 1 defines mucosal healing; a subscore of 0 is associated with better outcomes than 1, which is why some trials now require complete endoscopic normalisation.

How it compares

Mayo Score vs UCEIS (Ulcerative Colitis Endoscopic Index of Severity)

UCEIS is the better endoscopic instrument — it scores three features separately with defined descriptors, where the Mayo endoscopic subscore compresses everything into one four-point judgement.

UCEIS grades vascular pattern, bleeding and erosions or ulcers as separate items, originally as an 11-point score and later simplified, and it was developed specifically because the Mayo endoscopic subscore has poor inter-observer agreement and bundles distinct findings together. AGA clinical practice guidance on endoscopic scoring in IBD favours UCEIS for that reason. The Mayo subscore persists because decades of trial data and treatment thresholds are expressed in it.

Mayo Score vs Montreal classification

They are complementary, not alternatives: Mayo measures how active the disease is now, Montreal records how extensive it is — and extent determines surveillance timing and route of therapy.

The Montreal classification assigns ulcerative colitis an extent (E1 proctitis, E2 left-sided, E3 extensive) and a severity band. Extent does not change with treatment in the way activity does, and it drives decisions the Mayo score cannot inform — whether topical therapy can reach the disease, and when colorectal cancer surveillance should begin. Both belong in the notes.

Open the Montreal classification calculator →

Mayo Score vs Harvey-Bradshaw Index

Different diseases: Mayo is for ulcerative colitis, Harvey-Bradshaw for Crohn's disease. Neither is validated in the other.

The two indices occupy the same role in their respective diseases — a simple activity measure used to define remission and response — but the items differ because the diseases do. Harvey-Bradshaw counts liquid stools without a cap and includes abdominal mass and extraintestinal complications; Mayo includes rectal bleeding and an endoscopic subscore. Applying one to the other's disease produces a number with no validated meaning.

Open the Harvey-Bradshaw Index calculator →

Pearls & pitfalls

  • Stool frequency is relative to the patient's own normal, not an absolute count. A patient whose baseline is three stools a day and who now passes four scores 1, not 2.
  • The endoscopic subscore is scored on the worst-affected segment, so it says nothing about extent. Record the Montreal extent separately.
  • Remission definitions differ. Many trials require both a total of 2 or below and no individual subscore above 1 — the total alone is a looser bar than most published remission rates used.
  • A subscore of 1 still means visible inflammation. Some trials now require 0, and a 0 predicts better outcomes than a 1.
  • The physician global assessment is the least reproducible item and can shift a patient a whole band between two assessors.
  • Symptoms and endoscopy diverge often. Continuing symptoms with a healed mucosa usually means coexisting irritable bowel syndrome, bile-acid diarrhoea or another cause — not treatment failure.
  • It is not a tool for acute severe colitis. A patient can score 11 or 12 and still need the Truelove and Witts criteria to decide about admission and intravenous steroids.

Critical actions

  • Record the endoscopic subscore separately, because it is the number that predicts long-term outcome and drives treatment decisions.
  • Use the partial score for routine follow-up rather than scoping repeatedly, then confirm healing endoscopically at defined points.
  • Exclude Clostridioides difficile and cytomegalovirus infection before escalating immunosuppression in moderate or severe activity.
  • Assess against Truelove and Witts criteria in anyone with severe activity, and involve surgeons early rather than late.
  • Do not accept symptomatic improvement as remission — confirm mucosal healing, since it predicts colectomy-free survival better than symptoms.
  • Investigate persisting symptoms with a healed mucosa for a non-inflammatory cause instead of escalating therapy.
  • Start colorectal cancer surveillance from eight years after symptom onset in extensive or left-sided disease, independently of the current score.

Why this score exists

The Mayo score was not designed as a clinical instrument — it was the outcome measure of a single 1987 mesalamine trial, and it became the field's standard by being adopted rather than by being validated for that purpose. Two consequences follow. The first is that its weaknesses were never designed out: the physician global assessment is subjective yet carries the same weight as the endoscopic appearance, and the endoscopic item is scored on the worst-affected segment, which ignores extent entirely. The second is that the definition of 'remission' in the literature is not stable — different trials have used the total alone, the total plus subscore constraints, or endoscopic normalisation, so two papers reporting Mayo remission rates may not be measuring the same thing. The AGA and others have since developed more rigorous endoscopic indices, notably UCEIS, precisely to address the endoscopic item's limitations.

About the creator

  • Kenneth W. Schroeder

    First author, 1987 trial

    Published the disease activity index — now known as the Mayo score — as the outcome measure of a randomised trial of coated oral 5-aminosalicylic acid.

Limitations

  • Never formally developed as a clinical instrument — it was the outcome measure of a single 1987 trial in 87 patients and became standard by adoption.
  • All four items are equally weighted, although the endoscopic subscore predicts long-term outcome far better than the symptom items.
  • The physician global assessment is subjective and the least reproducible component.
  • The endoscopic subscore has recognised inter-observer variability, which is the reason UCEIS was developed.
  • It ignores disease extent entirely, scoring only the worst-affected segment.
  • Remission is defined inconsistently across the literature, so reported remission rates are not always comparable.
  • It is not designed for or validated in acute severe ulcerative colitis, where Truelove and Witts criteria govern the admission decision.
  • Stool frequency relative to an individual baseline is difficult to standardise across a trial population.

If you are the patient

The Mayo score is how your team measures how active your ulcerative colitis is. It adds up four things, each scored from 0 to 3: how many more times a day you are opening your bowels than is normal for you, how much blood you are seeing, what the lining of your bowel looks like at colonoscopy, and your doctor's overall impression. The total runs from 0 to 12 — under 3 counts as remission, and higher numbers mean more active disease. In clinic your team can work out most of the score without a camera test, which is why they ask about stools and bleeding at every visit. The part that matters most for the long term is the camera test score, because feeling well and having a healed bowel lining are not the same thing — it is possible to feel much better while inflammation is still visible, and treating that properly now reduces problems later. That is also why your team may want a camera test even when you feel fine.

Frequently asked questions

What is the Mayo score for ulcerative colitis?#

The Mayo score grades ulcerative colitis activity from four items each scored 0 to 3 — stool frequency, rectal bleeding, endoscopic appearance and physician global assessment — giving a total from 0 to 12. It is the most widely used activity index in UC trials, which is why guideline thresholds are expressed in its terms.

What Mayo score is remission?#

A total of 2 or below is conventionally clinical remission. Most trial definitions are stricter, additionally requiring that no individual subscore exceeds 1 — so a total of 2 made up of a single endoscopic subscore of 2 would not qualify. Check which definition is being used before comparing to published remission rates.

What is the partial Mayo score?#

The partial Mayo score is the three non-endoscopic items — stool frequency, rectal bleeding and physician global assessment — giving a range of 0 to 9. It can be calculated at any clinic visit without a colonoscopy, correlates closely with the full score, and is the practical instrument for follow-up between endoscopic assessments.

What is the Mayo endoscopic subscore?#

It is the endoscopic item of the Mayo score on its own, from 0 (normal or inactive) to 3 (spontaneous bleeding and ulceration). Mucosal healing is conventionally defined as 0 or 1, and the subscore predicts colectomy-free survival and sustained remission better than symptom measures. A score of 0 is associated with better outcomes than 1.

What is the maximum Mayo score?#

Twelve, from four items each scoring a maximum of 3. The partial Mayo score, which omits endoscopy, has a maximum of 9.

Is the Mayo score or UCEIS better for endoscopy?#

UCEIS is the more rigorous endoscopic instrument. It scores vascular pattern, bleeding and erosions or ulcers as separate defined items, and it was developed specifically because the Mayo endoscopic subscore compresses distinct findings into one judgement and has poor inter-observer agreement. The Mayo subscore remains in use because the historical trial evidence and treatment thresholds are written in it.

How is stool frequency scored in the Mayo score?#

Relative to the patient's own normal, not as an absolute count: 0 for normal, 1 for 1–2 more per day than usual, 2 for 3–4 more, and 3 for more than 4 above normal. Scoring it as an absolute number of stools per day is the commonest error in applying the index.

Can the Mayo score be used for Crohn's disease?#

No. It was developed and validated in ulcerative colitis, and includes rectal bleeding and a rectal endoscopic appearance that do not translate to Crohn's disease. Harvey-Bradshaw Index or CDAI are the corresponding instruments for Crohn's.

Related calculators

  • Montreal IBD — IBD classification — CD & UC
  • Harvey-Bradshaw — Crohn's disease activity index
  • PUCAI — Paediatric ulcerative colitis activity index

References

Original / primary reference

  1. Schroeder KW, Tremaine WJ, Ilstrup DM. Coated oral 5-aminosalicylic acid therapy for mildly to moderately active ulcerative colitis. A randomized study. N Engl J Med. 1987;317(26):1625-1629.

Endoscopic scoring and validation

  1. AGA Clinical Practice Update on Endoscopic Scoring Systems in Inflammatory Bowel Disease: Commentary. Clin Gastroenterol Hepatol. 2024.
  2. Travis SPL, Schnell D, Krzeski P, et al. Developing an instrument to assess the endoscopic severity of ulcerative colitis: the Ulcerative Colitis Endoscopic Index of Severity (UCEIS). Gut. 2012;61(4):535-542.

Clinical practice guidelines

  1. Rubin DT, Ananthakrishnan AN, Siegel CA, Sauer BG, Long MD. ACG Clinical Guideline: Ulcerative Colitis in Adults. Am J Gastroenterol. 2019;114(3):384-413.

Last updated July 29, 2026. Clinical knowledge base written and curated by GastroAGI Team from primary medical literature.

Written from primary literature and not yet independently clinically reviewed.

For use by qualified healthcare professionals. This calculator supports clinical judgement and does not replace it.