CT Abdomen Pelvis Venous Phase Protocol
The recommended protocol for a CT abdomen pelvis venous phase scan is a single-phase examination with IV contrast administered in the portal venous phase, typically acquired 70 seconds after contrast administration, without oral contrast unless specifically indicated. 1
Contrast Administration
- IV Contrast Type: Non-ionic iodinated contrast media (e.g., iohexol, ioversol)
- Contrast Volume: 100-150 mL (standard adult dose)
- Injection Rate: 3.0 mL/second (optimal flow rate for venous phase imaging) 2
- Timing: Portal venous phase imaging at approximately 70 seconds post-injection 1
Technical Parameters
- Slice Thickness: Thin slices (1-1.5 mm) for optimal image quality
- Scan Coverage: From the dome of the diaphragm through the pubic symphysis
- Patient Position: Supine with arms above head (if possible)
- Breathing Instructions: Breath hold during acquisition
Special Considerations
Oral Contrast
- Generally not required for routine venous phase imaging 1
- May be considered when:
- Bowel delineation is specifically needed
- Differentiation between bowel loops and adjacent structures is critical 1
- If needed, dilute iodinated contrast (6-9 mg Iodine/mL) can be used 3
Renal Function
- Check eGFR prior to contrast administration
- For patients with eGFR < 30 mL/min/1.73m², consider:
- Non-contrast CT
- Alternative imaging modalities
- Nephrology consultation 4
Common Pitfalls to Avoid
- Inadequate timing: Scanning too early may result in suboptimal venous enhancement
- Insufficient contrast volume: May lead to poor enhancement of vessels and organs
- Excessive delay: Waiting too long after contrast administration reduces vessel opacification
- Overlooking contraindications: Always check for history of severe contrast reactions
Evidence-Based Rationale
The portal venous phase (70 seconds post-injection) provides optimal visualization of abdominal and pelvic organs and vasculature for most diagnostic purposes 1. This timing allows for adequate enhancement of the liver parenchyma, portal and hepatic veins, and most abdominal viscera.
For specific clinical scenarios requiring arterial phase imaging (such as mesenteric ischemia or hypervascular lesions), a multiphasic protocol would be warranted 1, but for standard venous phase imaging, a single-phase examination is sufficient and reduces radiation exposure.
The American College of Radiology guidelines indicate that for routine surveillance and most diagnostic purposes, a single-phase examination in the portal venous phase is appropriate 1, with the venous phase providing the best overall assessment of abdominal and pelvic structures.