Forrest Classification of Upper GI Bleeding

Why use it

The Forrest class at endoscopy directly determines the need for endoscopic hemostatic therapy. High-risk stigmata (Ia, Ib, IIa) have rebleeding rates of 55–100% without treatment and require mandatory endoscopic hemostasis. Low-risk stigmata (IIc, III) have rebleeding rates <5–10% and can be safely managed without endoscopic therapy. The Forrest classification provides the foundation for evidence-based management of UGIB and is incorporated into ESGE, ACG, and BSG guidelines.

About

The Forrest Classification is the most widely used endoscopic classification system for acute upper gastrointestinal bleeding from peptic ulcers, developed by Forrest and colleagues in 1974. It categorizes bleeding stigmata (findings at endoscopy) into three major classes: Class I (active hemorrhage), Class II (recent hemorrhage with stigmata), and Class III (lesions without bleeding stigmata), each subdivided further. Class Ia is spurting arterial hemorrhage (highest risk), Ib is oozing non-spurting hemorrhage, IIa is a non-bleeding visible vessel, IIb is an adherent clot, IIc is a flat pigmented spot (hematin), and III is a clean-based ulcer. These classes correlate strongly with risk of rebleeding, need for surgical intervention, and mortality. The classification is universally used in clinical practice, guidelines, and clinical trials as a standardized framework for UGIB management.

When to use

• At upper endoscopy in any patient with acute non-variceal upper gastrointestinal bleeding
• Determining the need for endoscopic hemostatic therapy (clips, epinephrine injection, thermal therapy)
• Risk stratification for rebleeding, surgical intervention, and hospital length of stay
• Informing ICU admission vs. step-down unit vs. ward placement post-endoscopy
• Guiding timing of discharge and outpatient PPI therapy after successful hemostasis
• Clinical research and trial endpoint classification for upper GI bleeding studies

Formula

Pearls & pitfalls

• Forrest Ia and IIa have the HIGHEST rebleeding risk — without treatment, ~55–100% will rebleed. Endoscopic therapy is MANDATORY for these classes.
• A non-bleeding visible vessel (IIa) appears as a raised, red, blue, or purple protuberance in the ulcer base — it represents a pseudoaneurysm or clot plug over an artery.
• Adherent clot (IIb) management is controversial — ESGE recommends attempting clot removal with cold water irrigation ± gentle shearing; underlying visible vessel mandates treatment.
• Flat pigmented spot (IIc) has <10% rebleeding risk — medical management with high-dose PPI is sufficient; no endoscopic therapy needed.
• Clean-based ulcer (III) has <5% rebleeding risk — consider early discharge (within 24h) in low-risk patients (low Blatchford score, stable hemodynamics).
• Dual-modality endoscopic therapy (e.g., epinephrine + mechanical clip or thermocoagulation) is superior to monotherapy for Forrest Ia, Ib, and IIa lesions.
• High-dose IV PPI after endoscopic hemostasis (80 mg bolus + 8 mg/h for 72h) reduces rebleeding rates by ~20% compared to standard-dose PPI.
• Second-look endoscopy is NOT routinely recommended but may be considered if clinical signs of rebleeding develop post-procedure.
• The Glasgow-Blatchford Score (pre-endoscopy) and Forrest classification (post-endoscopy) are complementary — GBS guides urgency of endoscopy, Forrest guides treatment at endoscopy.

Next steps

Forrest Ia–Ib (Active Bleeding): Immediate endoscopic hemostatic therapy mandatory. Dual-modality approach (epinephrine injection + thermal/mechanical therapy). IV PPI (pantoprazole or omeprazole 80 mg bolus + 8 mg/h infusion for 72h). ICU monitoring. Surgical/interventional radiology backup. Forrest IIa (Non-bleeding Visible Vessel): Endoscopic therapy mandatory — 8× reduction in rebleeding. Dual therapy preferred. High-dose IV PPI × 72h. Hospital admission for monitoring. Forrest IIb (Adherent Clot): Gentle irrigation to remove clot; if underlying visible vessel → treat as IIa. If persistent clot: IV PPI and monitoring, with case-by-case decision on endoscopic treatment. Forrest IIc–III (Low-Risk Stigmata): No endoscopic therapy needed. Oral high-dose PPI. Early discharge in selected patients. Outpatient H. pylori eradication if positive.

Evidence

Forrest JAH et al. Endoscopy in gastrointestinal bleeding. Lancet. 1974;2(7877):394-397. PMID:4136718. Laine L, McQuaid KR. Endoscopic therapy for bleeding ulcers: an evidence-based approach based on meta-analyses of randomized controlled trials. Clin Gastroenterol Hepatol. 2009;7(1):33-47. PMID:18986845. Rebleeding rates: Ia 55–100%, Ib 55%, IIa 43–55%, IIb 22–33%, IIc 7–10%, III <5%. ESGE Guideline: Gralnek IM et al. Endoscopy in acute nonvariceal upper gastrointestinal hemorrhage. Endoscopy. 2015;47(10):a1-46.

References

1. Forrest JAH et al. Endoscopy in gastrointestinal bleeding. Lancet. 1974;2(7877):394-397. — link
2. Laine L, McQuaid KR. Endoscopic therapy for bleeding ulcers: an evidence-based approach based on meta-analyses of randomized controlled trials. Clin Gastroenterol Hepatol. 2009;7(1):33-47. — link
3. Gralnek IM et al. Diagnosis and management of nonvariceal upper gastrointestinal hemorrhage: European Society of Gastrointestinal Endoscopy (ESGE) Guideline. Endoscopy. 2015;47(10):a1-46. — link