What does a CT scan showing high‑density material in the stomach and small intestine indicate?

High-Density Material in Stomach and Small Intestine on CT

High-density material in the stomach and small intestine on CT most commonly represents ingested medications, oral contrast agents, or intraluminal blood—and distinguishing between these is critical because misidentifying medications or contrast as active gastrointestinal bleeding can lead to unnecessary interventions.

Primary Differential Diagnosis

Medications as Hyperdense Material

• Many commonly used oral medications appear hyperdense on CT scans and can mimic acute hemorrhage or contrast extravasation 1
• This is particularly problematic in CT angiography studies where positive enteric contrast should be avoided, as medication-related hyperdensities can decrease test sensitivity 1
• The presence of unexpected intraluminal hyperdensities may mask certain intra-abdominal pathologies, including urinary tract stones on plain CT or bowel ischemia on contrast-enhanced studies 1

Oral Contrast Material

• Positive oral contrast agents (high-density barium or iodinated contrast) will appear as hyperdense intraluminal material 2
• Neutral oral contrast agents (polyethylene glycol, sugar alcohol-based beverages, low-concentration barium) are preferred for CT enterography to avoid obscuring mucosal enhancement 2
• Positive oral contrast can obscure active gastrointestinal bleeding by masking contrast extravasation 2

Intraluminal Blood

• Active gastrointestinal bleeding appears as hyperdense material on noncontrast CT images (sentinel clot) and as contrast extravasation on arterial phase images 2
• Blood products accumulating at an ulcer site or in the gastric/duodenal lumen will demonstrate high attenuation 2
• Noncontrast images are essential to identify inherently hyperdense intraluminal material and differentiate it from active bleeding 2

Critical Diagnostic Approach

When Gastrointestinal Bleeding is Suspected

• CT angiography without and with IV contrast (multiphase protocol) is the examination of choice, with 85-90% sensitivity and 92% specificity for detecting active bleeding 2
• The noncontrast phase is mandatory to identify high-attenuation ingested material that can mimic bleeding 2
• Oral contrast should be avoided in suspected gastrointestinal bleeding because positive contrast renders the examination nondiagnostic and oral water can dilute intraluminal hemorrhage 2
• Multiphase acquisition (noncontrast + late arterial at 35 seconds + portal venous at 60-70 seconds) provides the highest sensitivity of 92% for detecting gastrointestinal bleeding 2

When Bowel Pathology is Suspected

• For suspected Crohn's disease or small bowel inflammation, CT enterography with neutral oral contrast and IV contrast is appropriate 2
• Neutral oral contrast (900-1,500 mL over 45-60 minutes) distends the bowel without obscuring mural hyperenhancement 2
• CT enterography has >80% sensitivity and >85% specificity for detecting active small bowel Crohn's disease 2

When Bowel Obstruction is Suspected

• CT abdomen and pelvis with IV contrast is the imaging modality of choice, with >90% diagnostic accuracy 3
• Oral contrast is generally not required for suspected high-grade obstruction, as nonopacified fluid in the bowel provides adequate intrinsic contrast 3, 4
• The presence of high-density material in dilated bowel loops may represent retained oral contrast, medications, or the "small bowel feces sign" indicating obstruction 3

Common Pitfalls and How to Avoid Them

Misinterpreting Medications as Bleeding

• Always obtain a detailed medication history before interpreting hyperdense intraluminal contents as hemorrhage 1
• If hyperdense material is present on noncontrast images but does not increase in attenuation or change configuration on arterial phase images, consider medications or retained contrast rather than active bleeding 1

Inadequate Bowel Distention

• Inadequate small bowel distention from insufficient oral contrast ingestion, gastric retention, or rapid transit can cause bowel collapse that mimics or obscures pathology 2, 5
• Collapsed jejunal segments are frequently problematic and may simulate wall thickening 5

Opaque Intraluminal Debris

• Opaque debris is especially problematic during multiphasic CT enterography for obscure gastrointestinal bleeding, as it can obscure true contrast extravasation 5
• Peristaltic contractions and transient intussusception can also create false-positive findings 5

Volume Averaging and Technical Factors

• Inadequate radiation dose or thick CT sections can result in false-negative examinations 5, 6
• Repeat scanning with thinner sections may be needed to accurately characterize small lesions or obtain accurate attenuation values 6

Clinical Decision Algorithm

1. Obtain medication history and determine if oral contrast was administered 1

2. If gastrointestinal bleeding is suspected clinically:

   • Order CT angiography (noncontrast + arterial + portal venous phases) without oral contrast 2
   • High-density material that increases in attenuation or changes configuration on arterial phase = active bleeding 2
   • High-density material unchanged from noncontrast to arterial phase = likely medication or retained contrast 1

3. If inflammatory bowel disease or small bowel pathology is suspected:

   • Order CT enterography with neutral oral contrast and IV contrast 2
   • High-density material in this context likely represents positive oral contrast (if given) or medications 1

4. If bowel obstruction is suspected:

   • Order CT abdomen/pelvis with IV contrast, no oral contrast needed 3
   • High-density material in dilated bowel may represent retained contrast, medications, or "small bowel feces sign" 3

5. When in doubt, correlate with clinical presentation, laboratory values (hemoglobin, lactate), and consider repeat imaging without oral contrast if initial study is equivocal 2, 1