What is the appropriate workup and management for a patient presenting with a gastrointestinal (GI) bleed?

GI Bleed Workup and Management

Immediate Hemodynamic Assessment

Calculate the shock index (heart rate ÷ systolic blood pressure) immediately upon presentation—a value >1 defines hemodynamic instability and mandates urgent CT angiography rather than routine endoscopy. 1, 2

• Place at least two large-bore intravenous catheters for rapid volume expansion 1
• Initiate crystalloid resuscitation to restore hemodynamic stability 1
• Use restrictive transfusion strategy with hemoglobin threshold of 7 g/dL (target 7-9 g/dL) for patients without cardiovascular disease 1, 2
• Use higher transfusion threshold of 8 g/dL (target ≥10 g/dL) for patients with cardiovascular disease 1, 3

Diagnostic Algorithm Based on Hemodynamic Status

For Hemodynamically Unstable Patients (Shock Index >1)

Perform CT angiography immediately as the first diagnostic test—this provides the fastest, least invasive means to localize bleeding and allows for immediate treatment planning. 4, 1, 2

• CTA should be performed in the arterial phase, not delayed/portal-venous phase 4
• Following positive CTA, proceed to catheter angiography with embolization within 60 minutes in centers with 24/7 interventional radiology 1, 2, 3
• Always consider an upper GI source in unstable patients, even with bright red rectal bleeding—perform upper endoscopy if CTA shows no lower GI source 4, 1, 3
• Colonoscopy is explicitly contraindicated as the initial approach when shock index >1 2

For Hemodynamically Stable Patients

Perform upper and lower GI endoscopy as the initial diagnostic procedures based on clinical presentation. 4, 1

For Suspected Lower GI Bleeding:

• Perform digital rectal examination to confirm blood and exclude anorectal pathology 2, 3
• Calculate Oakland score (age, gender, prior LGIB, rectal exam findings, heart rate, systolic BP, hemoglobin) 1, 2
  • Score ≤8: Safe for outpatient investigation 1, 2
  • Score >8: Requires hospital admission and colonoscopy 1, 2
• Perform colonoscopy within 24 hours after adequate bowel preparation using 4-6 liters of polyethylene glycol over 3-4 hours 4, 1, 2

For Suspected Upper GI Bleeding:

• Perform upper endoscopy within 24 hours of presentation 1
• Clinical predictors requiring urgent endoscopy include: age >65 years, shock, low hemoglobin, melena, fresh red blood in emesis or on rectal exam 1

Management of Obscure or Persistent Bleeding

If upper and lower endoscopy are negative but bleeding persists, video capsule endoscopy should be the next diagnostic modality, ideally performed within 48 hours when diagnostic yield is highest (87-91.9%). 4, 1

• Nuclear medicine scintigraphy offers 60-93% sensitivity for intermittent or slow bleeding when CTA and colonoscopy are negative 4
• Repeat CTA is unlikely to be beneficial unless bleeding becomes more brisk 4
• Mesenteric angiography is unlikely to be beneficial in the immediate setting for stable patients 4

Anticoagulation Management

For patients on warfarin with unstable GI hemorrhage, interrupt warfarin immediately and reverse with prothrombin complex concentrate plus vitamin K. 1, 2, 3

• Restart warfarin at 7 days after hemorrhage for patients with low thrombotic risk 1, 2, 3
• For high thrombotic risk patients, consider low molecular weight heparin at 48 hours 3
• For DOACs, interrupt immediately and use specific reversal agents (idarucizumab for dabigatran, andexanet for anti-factor Xa inhibitors) for life-threatening hemorrhage 2

Antiplatelet Management

• Permanently discontinue aspirin if used for primary prophylaxis 1, 2, 3
• Do not routinely stop aspirin for secondary prevention—if stopped, restart as soon as hemostasis is achieved 1, 2, 3
• If P2Y12 receptor antagonist is stopped, reinstate within 5 days to prevent thrombotic complications 3

Surgical Indications

Reserve surgery only for patients with hemorrhagic shock who fail resuscitation AND fail all attempts at radiological and endoscopic localization and intervention. 4, 2

• Blind segmental resection carries 33% rebleeding rates and 33-57% mortality 2
• Emergency subtotal colectomy carries 27-33% mortality 2
• Even in unstable patients, attempt localization with CTA or angiography before surgery to allow targeted treatment 2

Critical Pitfalls to Avoid

• Failing to consider upper GI source in hemodynamically unstable patients with hematochezia—this is the most common diagnostic error 4, 1, 2, 3
• Performing colonoscopy first in unstable patients (shock index >1) instead of CTA 4, 2
• Delaying endoscopy beyond 24 hours in high-risk stable patients 1
• Proceeding to surgery without attempting radiological localization 2
• Underestimating that mortality is primarily driven by comorbidity rather than exsanguination (overall mortality 3.4%, but 18% for inpatient-onset bleeding and 20% for patients requiring ≥4 units) 1, 2, 3

Special Considerations

Post-Polypectomy Bleeding:

• Colonoscopy should be performed rather than CTA as the bleeding source is already known 4
• Use two modalities for hemostasis (epinephrine plus one other), extrapolating from peptic ulcer literature 4

Toxic Megacolon with Bleeding:

• Persistent fever after 48-72 hours of steroids suggests perforation or abscess 4
• Free perforation, massive hemorrhage, or increasing transfusion requirements mandate urgent surgery 4