What is the role of Forrest classification, endoscopy, and angiography in managing gastrointestinal (GI) bleeding?

Management of Gastrointestinal Bleeding: Forrest Classification and Endoscopic vs Angiographic Approaches

For optimal patient outcomes in GI bleeding, endoscopy should be the first-line diagnostic and therapeutic approach for most patients, with angiography reserved for hemodynamically unstable patients with active bleeding or when endoscopy fails to identify or control the bleeding source.

Forrest Classification Basics

The Forrest classification is a standardized endoscopic classification system for bleeding peptic ulcers that guides risk stratification and management decisions:

• Forrest Ia: Spurting arterial bleeding - high risk of persistent bleeding or rebleeding, requires immediate endoscopic hemostasis 1
• Forrest Ib: Oozing bleeding - high risk of persistent bleeding or rebleeding, requires endoscopic hemostasis 1
• Forrest IIa: Non-bleeding visible vessel - high risk of rebleeding, requires endoscopic hemostasis 1
• Forrest IIb: Adherent clot - intermediate risk, consider endoscopic clot removal followed by hemostasis of any underlying vessel 1
• Forrest IIc: Flat pigmented spot - low risk of rebleeding, endoscopic hemostasis not recommended 1, 2
• Forrest III: Clean ulcer base - lowest risk of rebleeding, endoscopic hemostasis not recommended 1, 3

The Forrest classification has good inter-rater and intra-rater reliability among endoscopists and effectively predicts the risk of recurrent bleeding 3, 2.

When to Perform Endoscopy

Endoscopy is the first-line approach for most GI bleeding cases:

• Timing of endoscopy:

  • Early endoscopy (≤24 hours) is recommended following hemodynamic resuscitation 1
  • Very early endoscopy (<12 hours) should be considered for patients with high-risk features (hemodynamic instability despite resuscitation, in-hospital bloody emesis) 1

• Indications for urgent endoscopy:

  • Hemodynamically stable patients with suspected upper or lower GI bleeding 4
  • Patients with Oakland score >8 points should be admitted for colonoscopy (for lower GI bleeding) 5
  • Patients with high-risk Forrest lesions (Ia, Ib, IIa) require endoscopic hemostasis 1

• Benefits of endoscopy:

  • Both diagnostic and therapeutic capabilities in one procedure 4
  • Higher diagnostic yield compared to angiography (53.3% vs. 20.0%) 6
  • Ability to classify bleeding lesions using Forrest classification to guide management 3

When to Perform Angiography

Angiography should be reserved for specific clinical scenarios:

• Indications for immediate angiography:

  • Hemodynamically unstable patients (shock index >1) with suspected active bleeding 5
  • Patients with severe, unremitting bleeding who cannot undergo endoscopy 4
  • Failed endoscopic hemostasis after two attempts 1

• CT angiography (CTA) considerations:

  • CTA should be performed immediately in hemodynamically unstable patients as it provides the fastest means to localize bleeding 5
  • Following positive CTA, catheter angiography with embolization should be performed within 60 minutes for hemodynamically unstable patients 5
  • CTA prior to angiography provides a vascular roadmap that can improve targeting 4

• Conventional angiography characteristics:

  • Requires active bleeding at a rate of at least 1 mL/min for detection 4
  • Has 100% specificity but only 30-47% sensitivity 4
  • Allows for therapeutic intervention through embolization with technical success rates above 95% 4
  • Glue embolization appears to have better outcomes than microcoil embolization in preventing recurrent bleeding 4

Diagnostic and Management Algorithm

1. Initial assessment and resuscitation:

   • Assess hemodynamic status using shock index (heart rate/systolic BP) 5
   • Initiate volume resuscitation with crystalloid fluids if hemodynamically unstable 5
   • Apply restrictive transfusion strategy (Hb trigger 70 g/L, target 70-90 g/L) for stable patients without cardiovascular disease 5

2. Decision pathway:

   • If hemodynamically stable:

     • Perform early endoscopy (≤24 hours) 1
     • Apply Forrest classification for upper GI bleeding 1, 3
     • Provide endoscopic hemostasis for high-risk lesions (Forrest Ia, Ib, IIa) 1
     • Consider endoscopic clot removal for Forrest IIb lesions 1
     • No endoscopic hemostasis needed for low-risk lesions (Forrest IIc, III) 1

   • If hemodynamically unstable or severe active bleeding:

     • Perform immediate CTA 5
     • If CTA positive, proceed to catheter angiography with embolization 5
     • If CTA negative or bleeding source not identified, perform urgent endoscopy 4

3. For persistent or recurrent bleeding:

   • Repeat endoscopy with hemostasis if indicated 1
   • If second endoscopic attempt fails, proceed to angiographic embolization or surgery 1

4. For obscure GI bleeding (negative upper and lower endoscopy):

   • Consider video capsule endoscopy (VCE) which has higher diagnostic yield than angiography 6
   • VCE is most effective when performed within 48 hours of bleeding onset (diagnostic yield up to 87-91%) 4

Common Pitfalls and Caveats

• Failure to consider upper GI source in patients presenting with lower GI bleeding symptoms can lead to delayed diagnosis and treatment 5
• Delayed angiography after positive nuclear medicine studies reduces success rates - angiography should be performed within 1 hour of positive scintigraphy 4
• Relying solely on epinephrine injection for endoscopic hemostasis is inadequate - it should be combined with a second hemostatic modality 1
• Overlooking the timing of capsule endoscopy - diagnostic yield drops significantly if performed >3 days after bleeding presentation 4
• Mortality in GI bleeding is generally related to comorbidities rather than exsanguination, with in-hospital mortality of 3.4% overall but rising to 20% for patients requiring ≥4 units of red cells 5