What is the diagnostic approach for testing blood in vomitus (vomiting blood)?

Diagnostic Approach for Testing Blood in Vomitus

For patients with suspected hematemesis (vomiting blood), visual inspection of vomitus is the first-line diagnostic approach, with nasogastric tube lavage being a useful confirmatory test in ventilated patients when the diagnosis remains uncertain. 1

Initial Assessment

• Visual inspection of vomitus is the most immediate diagnostic test, with photographic documentation (of emesis basin, bedsheets) being increasingly helpful in confirming symptoms and guiding clinical decisions 1
• Differentiate between:
  • Coffee-ground appearance (partially digested blood) suggesting less active bleeding 2
  • Bright red blood suggesting active, ongoing bleeding 2
• Nasogastric tube (NGT) lavage in ventilated patients remains a useful test if blood return is shown, though this is not advised in unsedated patients due to risk of gagging, vomiting, and aerosolization 1

Laboratory Testing

• Complete blood count to assess for anemia and evaluate severity of blood loss 2
• Serum electrolytes and glucose to assess for metabolic derangements and dehydration 2
• Coagulation profile (PT/INR, PTT) to identify coagulopathies that may contribute to bleeding 1
• Liver function tests to rule out hepatic causes that may be associated with variceal bleeding 2
• Blood typing and cross-matching if significant blood loss is suspected or confirmed 1

Imaging Studies

• In hemodynamically stable cases where active upper GI bleeding is suspected but remains indeterminate, consider:
  • Computed tomography angiography (CTA) to identify active bleeding sites 1
  • Bedside real-time viewer capsule endoscopy as a less invasive alternative 1

Endoscopic Evaluation

• Esophagogastroduodenoscopy (EGD) is the gold standard for diagnosis of upper GI bleeding, allowing direct visualization and potential therapeutic intervention 2
• Consider urgent endoscopy for:
  • Hemodynamic instability despite resuscitation 1
  • Large volume hematemesis 1
  • Suspected variceal bleeding 1

Assessment of Bleeding Severity

• Established parameters for assessing acuity and severity of GI bleeding include:
  • Volume of visualized blood loss 1
  • Blood loss based on laboratory values (both absolute and relative to baseline) 1
  • Rate of blood loss 1
  • Response to transfusion 1
  • Hemodynamic stability 1

Special Considerations

• For patients on anticoagulants, assess the need for reversal agents if appropriate 1
• In critically ill patients, consider the possibility of prothrombotic disseminated intravascular coagulation, which may paradoxically increase risk of bleeding 1
• In patients with known liver disease, have a lower threshold for suspecting variceal bleeding 1

Common Pitfalls

• Failing to distinguish between hematemesis (vomiting blood) and hemoptysis (coughing up blood) 2
• Attributing positive guaiac-based tests only to lower GI tract bleeding when upper GI sources can also cause positive results 3
• Immunochemical fecal occult blood tests may not detect upper GI blood, while guaiac-based tests (especially sensitive ones like Hemoccult II SENSA) can detect small amounts of blood from the upper GI tract 3
• Delaying endoscopy in patients with significant hematemesis can lead to increased morbidity and mortality 1

Management Considerations

• Aggressive medical management should be individualized and may include:
  • Proton pump inhibitor infusions over intermittent intravenous administration 1
  • Octreotide infusions for patients with suspected or known liver disease 1
  • Scheduled antiemetics to prevent further vomiting and potential Mallory-Weiss tears 2
  • Correction of coagulopathies with platelets and/or clotting factors 1