What imaging is recommended to evaluate blood in vomit?

Imaging for Blood in Vomit (Hematemesis)

Endoscopy is the first-line diagnostic and therapeutic procedure for upper gastrointestinal bleeding and should be performed within 24 hours in most patients, with urgent endoscopy (within 6 hours) reserved for hemodynamically unstable patients. 1

Initial Diagnostic Approach

• Endoscopy is the primary tool for both diagnosis and treatment of upper GI bleeding, allowing direct visualization and immediate therapeutic intervention for bleeding sources 1, 2
• Upper endoscopy identifies common bleeding lesions including peptic ulcers, erosive esophagitis, Cameron's erosions, angioectasias, Dieulafoy's lesions, and gastric antral vascular ectasia 1
• Endoscopic therapy is indicated for major stigmata of recent hemorrhage (active bleeding, oozing, or visible vessel) and reduces rebleeding risk to approximately 10% with combination therapy 2

When Endoscopy Fails or Is Contraindicated

CT Angiography (CTA) - Preferred Imaging Modality

If endoscopy fails to identify a bleeding source or the patient remains hemodynamically unstable after initial resuscitation, CT angiography is the preferred next imaging study. 1

• CTA detects bleeding rates as slow as 0.3 mL/min with sensitivity of 79% and specificity of 95% 1
• A multiphase protocol (noncontrast, late arterial, and venous phases) is essential for detecting active hemorrhage 1
• In high-risk patients requiring ≥500 mL transfusion to maintain stability, MDCT sensitivity is 70.9% and specificity is 73.7%, with contrast extravasation being the most specific sign 3
• CTA provides rapid, minimally invasive localization before planning endoscopic or radiological therapy 3

Visceral Arteriography - Alternative with Therapeutic Capability

• Arteriography detects bleeding rates as low as 0.5 mL/min and allows simultaneous therapeutic embolization 1
• In postsurgical patients with new anastomotic sites, vascular edema, or perforation concerns, primary angiographic evaluation should be preferred over endoscopy 3, 1
• After positive CTA, catheter angiography with embolization should be performed within 60 minutes in hemodynamically unstable patients at centers with 24/7 interventional radiology 3

Imaging Modalities to Avoid

Barium/Contrast Upper GI Series - No Role in Acute Bleeding

Fluoroscopy with barium or iodinated oral contrast has no role in evaluating acute upper GI bleeding. 3, 1

• Positive oral contrast obscures active hemorrhage and interferes with subsequent endoscopy, angiography, or CT 3, 1
• Large volumes of neutral contrast can mask bleeding by dilution and are poorly tolerated by acutely ill patients 3

Tc-99m-Labeled RBC Scan - Limited Utility for Upper GI Bleeding

• Tagged RBC scans have high false-positive and false-negative rates specifically for upper GI bleeding 3
• Localization errors frequently occur when hemorrhage arises from gastric or duodenal sources 3
• Most patients appropriate for scintigraphy would have bleeding sources identifiable by endoscopy, leaving minimal clinical utility 3

Special Clinical Scenarios

Hemodynamically Unstable Patients

• If shock index (heart rate/systolic BP) remains >1 after initial resuscitation, CTA provides the fastest means to localize bleeding before therapy 3
• Since hemodynamic instability may indicate an upper GI source even in suspected lower GI bleeding, perform upper endoscopy immediately if CTA shows no source 3

Postsurgical or Traumatic Bleeding

• Primary angiographic evaluation is preferred when endoscopy is not feasible due to new anastomoses (bariatric surgery, tumor resection), vascular edema, or perforation risk 3, 1
• For suspected aortoenteric fistula, CTA with noncontrast, arterial, and portal venous phases (without oral contrast) is the most effective examination 3

Critical Pitfalls to Avoid

• Do not delay endoscopy in favor of imaging in stable patients—endoscopy remains first-line for diagnosis and treatment 1, 2
• Avoid oral contrast as it masks extravasation and compromises subsequent procedures 3, 1
• Do not proceed to emergency laparotomy unless every effort at radiological and endoscopic localization has been exhausted 3
• Recognize that intermittent bleeding may be missed by CTA or angiography, leading to false negatives 3