Can a computed tomography (CT) of the abdomen be performed with and without intravenous (IV) contrast?

CT Abdomen With and Without IV Contrast: Technical Feasibility and Clinical Indications

Yes, CT of the abdomen can be performed with and without IV contrast (dual-phase imaging), and this protocol is specifically recommended for certain clinical scenarios, most notably CT angiography (CTA) for gastrointestinal bleeding and evaluation of vascular complications. 1

Critical Distinction: CTA vs. Standard CT

The term "CT with and without contrast" has different meanings depending on the clinical context:

• CT angiography (CTA) without and with IV contrast is a distinct, specialized protocol that includes a non-contrast phase followed by optimized arterial-phase contrast imaging with thin collimation (≤1 mm) and 3D reconstructions 2
• Standard CT abdomen without and with IV contrast refers to routine non-contrast followed by portal venous phase imaging, which is less commonly indicated 1

When Dual-Phase Imaging Is Recommended

CTA Protocol (Non-Contrast + Contrast)

For gastrointestinal bleeding evaluation, CTA abdomen and pelvis without and with IV contrast is the preferred imaging modality when endoscopy is not performed or has failed 2:

• The non-contrast phase identifies baseline hyperdense material (sentinel clot) that could be mistaken for active extravasation on contrast-enhanced images 1
• CTA can detect bleeding rates as slow as 0.3 mL/min with sensitivity of 79-85% and specificity of 92-95% 2
• The American College of Radiology rates this protocol as "usually appropriate" (rating 8-9) for upper GI bleeding when endoscopy is contraindicated or unsuccessful 1

Post-Surgical or Traumatic Bleeding

CT abdomen without and with IV contrast may be considered for suspected postsurgical upper GI bleeding or hemobilia 1:

• In post-laparoscopic sleeve gastrectomy patients with bleeding, this protocol successfully diagnosed all surgical site pseudoaneurysms 1
• The non-contrast phase improves detection of small hyperdense hematomas that become isodense after contrast administration 3

When Dual-Phase Imaging Is NOT Necessary

Standard Abdominal CT Indications

For most acute abdominal conditions, IV contrast alone is sufficient and dual-phase imaging adds no diagnostic value 4:

• The American College of Radiology states there is "no significant literature supporting" routine use of CT abdomen without and with IV contrast for most clinical scenarios 1
• IV contrast alone is adequate for inflammatory conditions, suspected malignancy, and most trauma evaluations 4
• Studies show no significant difference in diagnostic accuracy between enhanced and unenhanced CT for acute abdominal processes (92.5% vs 92.5%, p > 0.05) 5

Specific Scenarios Where Dual-Phase Is Not Indicated

• Routine trauma evaluation: IV contrast-enhanced CT alone has 68% sensitivity and 97% specificity for hollow viscus injury 1
• Acute non-localized abdominal pain: IV contrast alone is recommended; oral contrast adds no benefit 4
• Suspected bowel obstruction or hernia: IV contrast alone enables detection of ischemia and vascular complications 4, 6

Clinical Decision Algorithm

Follow this approach when ordering abdominal CT:

1. Suspected active GI bleeding → Order CTA abdomen/pelvis without and with IV contrast (not standard CT) 2
2. Post-surgical bleeding or hemobilia → Consider CT abdomen without and with IV contrast 1
3. Blunt abdominal trauma with suspected visceral injury → IV contrast alone is usually sufficient; add non-contrast phase only if small hematomas need characterization 3, 7
4. Inflammatory conditions, malignancy, or acute abdomen → IV contrast alone 4, 8
5. Contraindication to IV contrast → Non-contrast CT alone, recognizing reduced sensitivity 4

Important Caveats

Common pitfalls to avoid:

• Do not confuse "CTA without and with IV contrast" with "standard CT without and with IV contrast"—these are different protocols with different indications 1, 2
• Adding a non-contrast phase to standard abdominal CT increases scan time by approximately 5.5 minutes and radiation exposure 3
• In blunt trauma, dual-phase imaging improves sensitivity from 74% to 92% (p ≤ 0.003) but primarily benefits patients requiring intensive conservative management rather than immediate surgery 3
• Virtual non-contrast images from dual-energy CT can potentially replace true non-contrast images but remain site-specific and are not universally accepted 1
• Adherence to ACR appropriateness criteria for IV contrast increases detection of urgent pathology by 49% and changes surgical plans in 25% of cases 4, 8

The bottom line: Dual-phase CT abdomen (without and with IV contrast) is technically feasible and specifically indicated for CTA protocols in GI bleeding and select post-surgical scenarios, but for most acute abdominal conditions, IV contrast-enhanced CT alone is the appropriate study.