What is the workup for a patient with a possible gastrointestinal (GI) bleed?

Workup for Possible Gastrointestinal Bleeding

The workup for a patient with possible gastrointestinal bleeding should begin with immediate hemodynamic assessment, followed by CT angiography for unstable patients or endoscopy within 24 hours for stable patients, with specific diagnostic pathways determined by suspected bleeding location. 1

Initial Assessment and Stabilization

• Hemodynamic evaluation: Check vital signs to identify shock (pulse >100 beats/min, systolic BP <100 mmHg) and assess for orthostatic changes 1
• Laboratory tests: Order complete blood count, basic metabolic panel, coagulation panel, and liver tests 2
• Resuscitation measures:
  • Rapid infusion of IV fluids for hypovolemia
  • Blood transfusion when hemoglobin is <7-8 g/dL 1, 3
  • Start high-dose proton pump inhibitor therapy while awaiting definitive diagnosis 1

Risk Stratification

• High-risk factors: Age >60 years, hemodynamic instability, active bleeding, comorbidities 1
• Clinical prediction tools: Use Glasgow-Blatchford bleeding score to determine risk level and appropriate management setting (inpatient vs. outpatient) 2

Diagnostic Pathway

For Hemodynamically Unstable Patients:

1. CT Angiography (CTA) should be the first investigation for unstable patients with suspected active bleeding 4, 1

   • High sensitivity (80-90%) for detecting bleeding at rates of 0.3-1.0 mL/min 1
   • Provides anatomical localization of bleeding source

2. If CTA is negative or inconclusive:

   • Consider conventional angiography if bleeding remains active 1
   • Success rate of 80-90% for detecting bleeding source 1

For Hemodynamically Stable Patients:

1. Upper GI Endoscopy within 24 hours for suspected upper GI bleeding 1, 3

   • Earlier endoscopy (within 12 hours) for high-risk patients
   • Indications for upper GI source: brisk rectal bleeding with hemodynamic compromise, history of peptic ulcer disease, portal hypertension, elevated BUN/creatinine ratio 4

2. Colonoscopy within 24 hours after adequate bowel preparation for suspected lower GI bleeding 5

3. If initial endoscopy is negative:

   • Video Capsule Endoscopy (VCE) for suspected small bowel bleeding
     • Highest yield when performed within 48 hours of bleeding episode (87-91.9% diagnostic yield) 4
     • Diagnostic yield drops to <50% if performed after 3 days 4

4. Nuclear Medicine Studies (tagged RBC scintigraphy)

   • Consider when other modalities are negative
   • Sensitivity of 60-93% for detecting intermittent or slow bleeding 4
   • Less anatomical precision than CTA 4

Special Considerations

Medication Management

• Antiplatelet therapy: Consult cardiology before making changes, especially for patients with coronary stents 1
• Anticoagulants:
  • Warfarin should be interrupted and reversed with prothrombin complex and vitamin K in unstable bleeding 1
  • Direct oral anticoagulants should be interrupted and considered for reversal agents in life-threatening hemorrhage 1
• NSAIDs: Discontinue as they can exacerbate GI bleeding 1

Post-Polypectomy Bleeding

• Colonoscopy should be the first-line investigation and treatment rather than CTA 4
• Consider combination therapy with epinephrine and another modality 4

Pitfalls and Caveats

• Don't miss upper GI sources in patients with rectal bleeding - up to 15% of patients with suspected lower GI bleeding ultimately have an upper GI source 4
• Avoid nasogastric tube placement in suspected upper GI bleeding as it doesn't reliably aid diagnosis, doesn't affect outcomes, and has complications in up to one-third of patients 4
• Don't delay VCE if indicated - diagnostic yield is highest when performed within 48 hours of bleeding 4
• Limitations of VCE include lack of therapeutic capabilities, inability to control movement, difficulty in localizing lesions, and risk of capsule retention (2% of patients) 4
• Mesenteric angiography is unlikely to be beneficial if performed within 24 hours of a negative CTA 4

By following this structured approach to the workup of possible GI bleeding, clinicians can efficiently identify the source of bleeding and initiate appropriate treatment to reduce morbidity and mortality.