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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
  2. /
  3. Forrest Classification
GI Bleeding

Forrest Classification

Peptic ulcer bleeding — rebleeding risk at endoscopy

Class I is active bleeding, class II shows stigmata of recent haemorrhage, and class III is a clean base with no stigmata.

A descriptive endoscopic classification, not an additive score — select what you saw at endoscopy. It predicts rebleeding well, particularly for gastric ulcers, but it does not predict mortality.

When to use
Use it at the index endoscopy for a bleeding peptic ulcer, to decide whether to apply endoscopic haemostasis and how intensively to monitor afterwards. It is the language that connects the endoscopic finding to the management decision: high-risk stigmata are treated and admitted for observation, low-risk lesions are not treated and often allow early feeding and discharge. It applies specifically to peptic ulcers, not to varices, Mallory-Weiss tears or other sources, and it speaks to rebleeding — for a mortality estimate you need the Rockall score, and for the pre-endoscopy triage decision the Glasgow-Blatchford score.
Why use it
Because the endoscopic appearance of an ulcer is the strongest single predictor of whether it will bleed again, and Forrest turns that appearance into a consistent, shared vocabulary that drives a clear treatment rule. Grouping ulcers this way is what underpins the modern standard of care: treat high-risk stigmata endoscopically and give high-dose proton pump inhibitor therapy, leave low-risk lesions alone and consider early discharge. Without a common classification, the same ulcer would be described five different ways and managed five different ways.
Formula, evidence and interpretation

About the Forrest Classification of Peptic Ulcer Bleeding

The Forrest classification describes what a bleeding peptic ulcer looks like at endoscopy and maps that appearance to the risk of rebleeding. Class I is active bleeding (Ia spurting, Ib oozing); class II shows stigmata of recent haemorrhage (IIa non-bleeding visible vessel, IIb adherent clot, IIc flat pigmented spot); class III is a clean ulcer base. Rebleeding risk without endoscopic therapy falls from as high as 55–90% for a spurting vessel and 40–50% for a visible vessel down to roughly 5% for a clean base. High-risk stigmata — Ia, Ib and IIa — should be treated endoscopically; IIc and III need none. It is a descriptive classification, not an additive score, and it predicts rebleeding rather than death.

On this page

  • 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

Interpreting the result

Read the class as a rebleeding risk and a treatment instruction in one. Ia, Ib and IIa are high-risk stigmata: apply endoscopic haemostasis — combination therapy or a mechanical/thermal method rather than adrenaline alone — and give high-dose intravenous proton pump inhibitor afterwards. IIb (adherent clot) is intermediate and handled according to local practice, either clot removal and treatment of what lies beneath or PPI therapy alone. IIc and III are low risk, need no endoscopic therapy, and support oral PPI, early feeding and early discharge. Across all classes, test for and eradicate Helicobacter pylori and review NSAID and antiplatelet use.

ScoreBandWhat it meansAction
IaActive spurting — high riskRebleeding ~55–90% without endoscopic therapyImmediate endoscopic haemostasis + high-dose IV PPI; admit and monitor
IbActive oozing — high riskRebleeding ~50% without endoscopic therapyEndoscopic haemostasis + high-dose IV PPI; admit and monitor
IIaNon-bleeding visible vessel — high riskRebleeding ~40–50% without endoscopic therapyTreat endoscopically despite no active bleeding; high-dose IV PPI
IIbAdherent clot — intermediate riskRebleeding ~20–30% without endoscopic therapyConsider clot removal and treat the base, or high-dose PPI alone; admit
IIcFlat pigmented spot — low riskRebleeding ~7–10%No endoscopic therapy; oral PPI, early feeding, consider discharge
IIIClean base — low riskRebleeding ~3–5%No endoscopic therapy; oral PPI and early discharge usually appropriate

What the Forrest Classification needs (6 inputs)

Class Ia — spurting arterial bleeding
Active, pulsatile arterial haemorrhage. The highest-risk appearance and an unambiguous indication for immediate endoscopic haemostasis.
Class Ib — oozing bleeding
Active non-pulsatile oozing from the ulcer base without a discrete spurting point. Still active bleeding and still treated.
Class IIa — non-bleeding visible vessel
A protuberant, pigmented or pearl-like vessel in the ulcer base that is not currently bleeding. High rebleeding risk, so it is treated despite the absence of active bleeding.
Class IIb — adherent clot
A clot adherent to the base that resists vigorous washing. Intermediate risk; management is debated between clot removal with treatment of the underlying lesion and intensive PPI therapy alone.
Class IIc — flat pigmented spot
A flat red or black spot in the ulcer base — a low-risk stigma that does not require endoscopic therapy.
Class III — clean ulcer base
No stigmata of recent haemorrhage. The lowest-risk appearance; no endoscopic treatment needed and early discharge is usually appropriate.

What it returns

Forrest class
The single descriptive category that best matches what was seen at endoscopy.
Rebleeding risk band
High (Ia, Ib, IIa), intermediate (IIb) or low (IIc, III), which drives whether endoscopic therapy is indicated.

How it is calculated

Forrest is a lookup, not a calculation: the endoscopist selects the appearance that best fits the ulcer, and that category carries an approximate untreated rebleeding risk drawn from decades of natural-history and trial data. The classification splits ulcers into three tiers — actively bleeding (I), recently bled with stigmata (II), and clean (III) — and the class II tier is further graded because a visible vessel, an adherent clot and a flat spot behave very differently. The clinical rule follows directly: the higher tiers are treated endoscopically and the lower ones are not.

Facts & figures

Forrest class, stigma and approximate untreated rebleeding risk
ClassEndoscopic appearanceRebleeding (untreated)Endoscopic therapy?
IaSpurting arterial bleeding~55–90%Yes
IbOozing bleeding~50%Yes
IIaNon-bleeding visible vessel~40–50%Yes
IIbAdherent clot~20–30%Consider
IIcFlat pigmented spot~7–10%No
IIIClean base~3–5%No

Percentages are the historical untreated risks reported across natural-history series; endoscopic therapy and high-dose PPI reduce them substantially.

Evidence

Original description

1974

Forrest, Finlayson and Shearman proposed the classification in 1974 to standardise the endoscopic description of gastrointestinal bleeding lesions, distinguishing active bleeding, stigmata of recent haemorrhage and clean lesions.

The scheme's enduring value is that the appearance it captures is the dominant predictor of rebleeding, later quantified across many cohorts and used to define which lesions benefit from endoscopic therapy.

Predictors of recurrent haemorrhage — systematic review

2008

Systematic review of the predictors of recurrent bleeding after endoscopic haemostatic therapy for bleeding peptic ulcers, pooling the stigmata-specific rebleeding rates.

Active bleeding and a non-bleeding visible vessel carried the highest rebleeding risk after therapy, confirming the class I / IIa grouping as the high-risk tier that justifies treatment.

Natural history and management review

1994

Foundational clinical review synthesising the natural history of bleeding peptic ulcers by endoscopic stigma and the effect of endoscopic therapy.

Reported the classic untreated rebleeding gradient — from a clean base at roughly 5% up to an actively spurting vessel at the highest risk — that Forrest classes summarise.

How it compares

Forrest Classification vs Rockall Score

Forrest predicts rebleeding from the endoscopic appearance; Rockall predicts mortality by adding age, shock and comorbidity to the endoscopic findings — use them together after endoscopy.

The full Rockall score actually incorporates the same endoscopic stigmata that Forrest describes, but wraps them in patient-level risk factors to estimate death rather than rebleeding. In practice the endoscopist assigns a Forrest class to drive the immediate treatment decision, and the Rockall score is calculated for prognosis and disposition. They are complementary readings of the same endoscopy.

Open the Rockall Score calculator →

Forrest Classification vs Glasgow-Blatchford Score

Glasgow-Blatchford is a pre-endoscopy triage score with no endoscopic input; Forrest is an at-endoscopy classification — they operate at different moments and do not compete.

Glasgow-Blatchford decides, before any scope, who needs admission or intervention and who might be discharged. Forrest is only available once the ulcer has been seen, and it decides whether to treat it and how closely to watch afterwards. A patient can have a high Glasgow-Blatchford score and then a reassuring Forrest III clean base, or vice versa.

Open the Glasgow-Blatchford Score calculator →

Pearls & pitfalls

  • Forrest predicts rebleeding, not mortality. For a mortality estimate use the Rockall score, which adds age and comorbidity.
  • Class IIb (adherent clot) is the contentious one: vigorous washing may expose a treatable Ia/Ib/IIa lesion, and practice varies between clot removal with treatment and high-dose PPI alone.
  • A 'visible vessel' (IIa) is a stigma to treat even though nothing is actively bleeding — its untreated rebleeding risk is high.
  • Interobserver agreement is only moderate, particularly in telling an adherent clot from a flat spot; when in doubt, treat the higher-risk interpretation.
  • The classification applies to peptic ulcers; do not force varices, Dieulafoy lesions or Mallory-Weiss tears into it.
  • The quoted rebleeding percentages are untreated natural-history figures — endoscopic therapy plus high-dose PPI markedly lowers them, so they describe risk, not the expected outcome after treatment.

Critical actions

  • Apply endoscopic haemostasis to Forrest Ia, Ib and IIa lesions, using a mechanical or thermal method combined with adrenaline rather than adrenaline injection alone.
  • Give high-dose intravenous proton pump inhibitor therapy after treating a high-risk stigma.
  • For an adherent clot (IIb), decide between clot removal with treatment of the underlying lesion and intensive PPI therapy, per local protocol, and admit for monitoring.
  • For IIc and III lesions, withhold endoscopic therapy and consider early feeding and discharge on oral PPI.
  • In every case, test for Helicobacter pylori and eradicate if positive, and review NSAID, aspirin and anticoagulant use.

Why this score exists

The original 1974 paper set out to bring order to how endoscopists described bleeding lesions, at a time when flexible endoscopy was new and its findings were recorded inconsistently. The lasting insight is that the look of the ulcer — spurting, oozing, a naked vessel, a clot, a spot, or nothing — encodes its future behaviour, so a shared descriptive language is also a shared risk language. Everything that followed, from the visible-vessel treatment rule to high-dose PPI protocols, is built on that classification.

About the creator

  • John A. H. Forrest

    First author, 1974 classification

    Published the endoscopic classification of bleeding peptic ulcer stigmata still used to guide haemostatic therapy. Not to be confused with Ewan H. Forrest, who derived the Glasgow Alcoholic Hepatitis Score.

Limitations

  • It is descriptive and subjective, with only moderate interobserver agreement for the intermediate stigmata.
  • It predicts rebleeding but not mortality, and takes no account of age, comorbidity or haemodynamics.
  • The rebleeding percentages attached to each class are historical, untreated figures and vary between series.
  • It applies to peptic ulcers only, and does not describe other bleeding sources.
  • The management of the adherent-clot class (IIb) remains genuinely uncertain, so the classification does not settle every treatment decision.

If you are the patient

During an endoscopy for a bleeding stomach or duodenal ulcer, the doctor looks closely at the ulcer and puts its appearance into one of the Forrest categories, from a vessel that is actively spurting (highest risk of bleeding again) through to a clean-looking base (lowest risk). This tells the team whether to treat the ulcer there and then — for example by sealing a vessel with a clip or heat and injecting medication — and how carefully to watch you afterwards. High-risk appearances are treated and usually need a night or two of monitoring; low-risk ones often need no treatment and mean you can eat and go home sooner. It describes the ulcer's risk of bleeding again, rather than any other kind of risk, and it usually comes with tests for the Helicobacter pylori bug and a review of any anti-inflammatory or blood-thinning medicines.

Frequently asked questions

What is the Forrest classification?#

It is an endoscopic classification of bleeding peptic ulcers that groups them by appearance — active spurting (Ia) or oozing (Ib) bleeding, a non-bleeding visible vessel (IIa), an adherent clot (IIb), a flat pigmented spot (IIc), or a clean base (III) — and links each to a rebleeding risk and a treatment decision.

Which Forrest classes need endoscopic treatment?#

The high-risk stigmata — Forrest Ia, Ib and IIa — should be treated with endoscopic haemostasis and high-dose proton pump inhibitor therapy. IIc and III are low risk and need no endoscopic therapy. IIb (adherent clot) is intermediate and managed according to local protocol.

What is the rebleeding risk for each Forrest class?#

Without endoscopic therapy, approximate rebleeding risks are ~55–90% for Ia, ~50% for Ib, ~40–50% for IIa, ~20–30% for IIb, ~7–10% for IIc and ~3–5% for III. These are untreated natural-history figures; treatment lowers them considerably.

Does the Forrest classification predict death?#

No — it predicts rebleeding, not mortality. To estimate mortality after an upper GI bleed, use the Rockall score, which combines the endoscopic findings with age, shock and comorbidity.

What is a Forrest IIa lesion?#

A non-bleeding visible vessel: a protuberant, pigmented vessel in the ulcer base that is not currently bleeding. Despite the absence of active bleeding it carries a high rebleeding risk (about 40–50% untreated) and is treated endoscopically.

Why is the adherent clot (IIb) controversial?#

Because washing the clot away may reveal a higher-risk lesion that benefits from treatment, but doing so can also provoke bleeding. Some endoscopists remove the clot and treat what is underneath, while others manage it with high-dose PPI therapy alone; the evidence does not clearly favour one approach.

Related calculators

  • Rockall Score — GI bleed rebleeding & mortality risk
  • Glasgow-Blatchford — Upper GI bleed risk stratification
  • AIMS65 Score — Upper GI bleed mortality — five bedside criteria
  • EGUS (Gastric Ulcer) — Malignancy risk in a gastric ulcer, and who needs repeat endoscopy

References

Original / primary reference

  1. Forrest JAH, Finlayson NDC, Shearman DJC. Endoscopy in gastrointestinal bleeding. Lancet. 1974;2(7877):394-397.

Validation and evidence

  1. Elmunzer BJ, Young SD, Inadomi JM, Schoenfeld P, Laine L. Systematic review of the predictors of recurrent hemorrhage after endoscopic hemostatic therapy for bleeding peptic ulcers. Am J Gastroenterol. 2008;103(10):2625-2632.
  2. Laine L, Peterson WL. Bleeding peptic ulcer. N Engl J Med. 1994;331(11):717-727.

Clinical practice guidelines

  1. Laine L, Barkun AN, Saltzman JR, Martel M, Leontiadis GI. ACG Clinical Guideline: Upper Gastrointestinal and Ulcer Bleeding. Am J Gastroenterol. 2021;116(5):899-917.
  2. Gralnek IM, Stanley AJ, Morris AJ, et al. Endoscopic diagnosis and management of nonvariceal upper gastrointestinal hemorrhage (NVUGIH): ESGE Guideline – Update 2021. Endoscopy. 2021;53(3):300-332.
  3. Barkun AN, Almadi M, Kuipers EJ, et al. Management of Nonvariceal Upper Gastrointestinal Bleeding: Guideline Recommendations From the International Consensus Group. Ann Intern Med. 2019;171(11):805-822.

Further reading

  1. Sung JJY, Chiu PWY, Chan FKL, et al. Asia-Pacific working group consensus on non-variceal upper gastrointestinal bleeding: an update 2018. Gut. 2018;67(10):1757-1768.

Last updated July 30, 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.