Stratifies rebleeding risk to determine inpatient monitoring intensity.
ESGE, ACG, and BSG standard for endoscopic reporting of ulcer haemorrhage.
Section 2
Formula & Logic
Forrest Classification System
Class
Endoscopic Finding
30-day Rebleeding Risk
Ia
Spurting haemorrhage
55%
Ib
Oozing haemorrhage
55%
IIa
Non-bleeding visible vessel (NBVV)
43%
IIb
Adherent clot over ulcer
22%
IIc
Flat pigmented spot
10%
III
Clean-based ulcer
5%
Endoscopic Treatment Threshold
Ia, Ib, IIa: High risk — endoscopic treatment is mandatory.
IIb (adherent clot): Intermediate risk — clot removal ± treatment; evidence supports irrigation and removal of clot then treat base if NBVV present.
IIc, III: Low risk — endoscopic treatment not indicated; medical management and safe discharge consideration.
Section 3
Pearls/Pitfalls
Combination Endoscopic Therapy
For Forrest Ia/Ib/IIa: Use dual endoscopic therapy — adrenaline (epinephrine) injection PLUS mechanical (clips) or thermal modality.
Adrenaline alone is insufficient and not recommended as monotherapy per ESGE guidelines.
Over-the-scope clips (OTSCs) have superior haemostasis rates for Forrest Ia/IIa vs. through-the-scope clips.
High Dose PPI Post-Endoscopy
For Forrest Ia, Ib, IIa: Give high-dose PPI infusion (e.g. omeprazole 80mg bolus then 8mg/hr for 72h) after endoscopic haemostasis to reduce rebleeding and mortality.
Section 4
Next Steps
Post-Endoscopy Management
01
Forrest Ia/Ib/IIa: High-dose IV PPI 72h → oral PPI; inpatient 72h minimum with serial Hb checks.
02
Forrest IIb: Admit 24–48h; oral high-dose PPI; repeat endoscopy at 72h if clinically indicated.
03
Forrest IIc/III: Consider discharge with oral PPI; ensure H. pylori testing.
04
All patients: Identify and stop offending drugs (NSAIDs, antiplatelet); H. pylori test and treat.
Section 5
Evidence Appraisal
Primary Reference
Endoscopy in gastrointestinal bleeding
Forrest JA et al. • Lancet. 1974;2(7877): 394–397
Management of Nonvariceal Upper Gastrointestinal Bleeding: Guideline Recommendations From the International Consensus Group
Barkun AN et al. • Annals of Internal Medicine. 2019;171(11): 805–822
Section 6
Literature
Development
Described by James Forrest, Neil Finlayson, and David Shearman at the Western General Hospital, Edinburgh, and published in The Lancet in 1974. The classification arose from the first systematic endoscopic study of bleeding peptic ulcers, characterising the appearance of the bleeding vessel and correlating endoscopic findings with clinical outcomes. The paper was a landmark in establishing therapeutic endoscopy as a clinical discipline.
Enduring Relevance
The Forrest Classification is one of the oldest endoscopic classification systems still in active clinical use, endorsed by ESGE, BSG, and ACG for 50+ years. It underpins the evidence base for endoscopic haemostasis and high-dose PPI protocols after peptic ulcer bleeding. Modern refinements including numerical rebleeding risk data and the demonstration of superiority of dual vs. mono endoscopic therapy have built directly on the Forrest framework.
